Benjamin Britten was born 100 years ago this month. He was a shy, repressed, middle-class Englishman from Lowestoft in Suffolk, who somehow became one of the greatest composers of the 20th century.

Before we get into how Britten was so awesome, there's a bit of reputational yard-clearing to be done. If you know little about classical music, then congratulations, this article is for you, but you probably don’t know that for much of his life and since his death, Britten's reputation in the classical world has been contaminated with dodgy and more or less half-baked notions of Britishness. To be fair, he didn’t exactly discourage this. He strongly believed that composers ought to be socially useful, and seldom turned down a commission, and so a lot of his pieces were commissioned by this or that national institution. He was the first British composer to be made a life peer. He refused the offer of Master of the Queen’s Music, only on the grounds that he was too ill to fulfil the duties of the job. In almost every respect, he was Establishment. And yet I know at least one highly respected avant-garde musician, a connoisseur of and expert in all manner of improvisational noise, who’s said to me as if betraying a confidence, ‘You know, I actually really like Britten.’

People like Britten for all sorts of different reasons – well, people like music for all sorts of different reasons – but one of the reasons why his music has the power to move people who have no time for the whole Britishness thing is that, although Britten was very much a middle-class Englishman of his time, he was also something else. He may have liked cold baths and rice pudding, but he was also a Labour voter back when that meant something, and a pacifist in WWII when that really meant something. Although he appreciated English folk music he was also cosmopolitan, eagerly absorbing the European avant-garde in his youth and Balinese gamelan in middle age. And he was also a gay man at a time when to be one was a criminal offence, which we’ll get to in a minute.

He was born the beloved youngest son of a frustrated dentist and a talented amateur singer. He was marked out early on as a gifted pianist and composer, and won a scholarship to the Royal College of Music. As a teenager he was firmly progressive, admiring Mahler as well as Schoenberg's student Alban Berg, and had little time for countrymen such as Vaughan Williams and Elgar. He grew to maturity in the 30s, getting a job as in-house composer for what seems now like a spectacularly unlikely public sector organisation, the GPO Film Unit. Here he met the poet WH Auden, who played a significant role in encouraging Britten to recognise his own attraction to men – and, more uncomfortably for Britten himself and for posterity, to teenage boys.

In the late 1930s he met the singer Peter Pears, who quickly became his lifelong partner, and over the course of their long careers the two became public figures, as well as one of the longest-lasting couples in British music. What might seem weird now is that they never came out, in the modern sense; but back then, nobody did. When Britten was a young man, British law regarded sex between males of any age as a criminal offence, and it went on doing so until 1968, only eight years before he died. The fact that nobody outed Britten and Pears is a sign of how long ago the mid-20th century was, even though anybody who met them knew the story. A chap didn’t blab about who another chap slept with, especially when the other chap was a national treasure. As proof of how open a secret it was, when Britten died, Buckingham Palace sent the official telegram of sympathy not to his surviving siblings, but to Pears.

Britten’s attraction to teenage boys is problematic. It wasn't only sexual, or even always sexual, but seems to have been tied up with his notions about innocence and childhood. As you might expect, everybody who knew anything about this aspect of his sexuality has been interviewed at length about it, and the main reason why the tabloids haven't made him a posthumous target is that there's nothing to be furious about: on the very few occasions when he made a rather tentative pass, he was turned down, and that was the end of that. It's still the case that nearly every article about Britten either uses his sexuality to explain him, or tries to make excuses for it, and that's got something to do with how the most obvious recurring theme in Britten’s music is that of guilt and innocence.

Consider another major gay English artist, the filmmaker Derek Jarman. Jarman adored the sight of handsome young men and never got tired of pointing a camera at them. That capacity for outspoken, guilt-free sexual desire was a powerfully political element in Jarman's work, because when he was active, successive Tory governments were eagerly promoting institutionalised homophobia. By contrast, Britten, like a lot of men of his generation, tended to experience the conflict between his personal desires and the rules of society as something that was wrong with him. One of the most gripping and moving elements in his music is his effort to deal with this conflict: the ways in which he takes his most personal longings and fears, and finds vivid and haunting ways of bringing them home to us, asking questions for which we maybe don't have answers. Leonard Bernstein – another gay man who felt that he couldn’t ever come out – talked with great sympathy about the pain in Britten’s work, and although much of Britten’s music is serene, cheerful or otherwise suitable for performances by amateur choirs, a lot of the best of it is about darkness and violence.

It's impossible to give an overview of such a prolific composer so we’re focusing instead on just three works: a song cycle, an opera and a requiem mass. Most of Britten’s best work was written to be sung, and although he wrote some wonderful instrumental music, nothing inspired him like the human voice.

Serenade for Tenor, Horn and Strings Op 31 (1943)

If you only listen to one work by Britten, it should be this: settings of six English poems, bookended by an instrumental prologue and an identical epilogue, scored for a tenor voice, a French horn and a small string orchestra. What unifies the poems is that they're all about night; Serenade is about what happens when the sun goes down.

From the prologue, there’s something subtly off about the music. Written for solo horn, it's a slow fanfare played entirely on the horn's natural harmonics. But our ears are used to a somewhat different tuning system called equal temperament, so we hear the horn as sounding slightly out of tune. That canny use of the audible difference between natural harmonics and the social compromise of equal temperament is one of the first of Britten's brilliant strokes in this piece.

The first two songs, ‘Pastoral’ and ‘Nocturne’, are settings of poems by Charles Cotton and Tennyson. These represent the process of falling asleep; ‘Pastoral’ is a child's-eye view of a sunset, with the setting sun making even small things cast long shadows, so that an ant looks like an elephant. ‘Nocturne’ is like a half-remembered heroic dream, with intense but fuzzy intimations of an epic story and the horn imitating a leaping bugle, but the repeated refrain of the echoes ‘dying, dying, dying’ is the only thing the sleeper can remember before falling back to sleep again.

‘Elegy’, a setting of William Blake's ‘The Sick Rose’, is where the whole thing rises to another level. The basic element is a string figure that pulses oddly on the off-beat, like a heartbeat out of sync with what you sense ought to be the basic pulse of the music (you can hear something similar in the introductory synth riff of LCD Sound System's ‘Someone Great’.) But then the horn sidles in, playing long-held notes that wooze upwards or downwards a semitone, tempting the strings to new harmonic territories. After only a minute of this, the strings and horns all but drop out, and the singer sings Blake's poem to an agonised, angular melody derived from the horn part. This is where Britten works his magic.

In popular music, loss of innocence is usually felt as a good thing, or at least not such a bad thing; think of all those 50s rock & roll songs dripping with lust, or the young Lou Reed's paeans to intoxication and S&M. In Britten, loss of innocence is usually a bad thing. Not always; his opera Albert Herring is a comedy about a meek young chap who by chance goes on a drunken spree, and in so doing learns self-confidence. But usually, Britten wants to protect innocence, and ‘Elegy’ is his first great lament for its loss. The last part of 'Elegy' is a stroke of genius; rather than try to develop the all-too-brief vocal part, Britten reprises the first part again, with a brief coda tacked on, as if to say: that's the way it is, boys and girls, invisible worms, it was ever thus.

The next piece, catchily titled ‘Dirge’, is a setting of an anonymous 15th century lyric in Yorkshire dialect called the Lyke-Wake Dirge. The poem is actually a warning to the listener that if you don't give to the poor, you'll pay for it when you die. The 60s folk-rock group Pentangle did a rather lovely version of it. Britten's version is a nightmare. It takes the lyric's mood of threatening damnation and underlines it using every trick in the early modernist book. The singer sings each verse to the same melody, and slowly the ensemble comes in underneath him, getting more and more angry and frantic with each verse, but also changing key beneath the singer, whose unchanging vocal melody is therefore given the harmonic equivalent of different lighting with each successive verse. With the mention of ‘Purgatory fire’, the ensemble starts to back off, as if intimidated, until by the final verse, the strings have all but dropped to a whisper.

The final song, ‘Sonnet’, renders John Keats' ‘O soft embalmer of the still midnight’ as a gorgeous love song to sleep itself. On the line about the poppy throwing around the sleeper's bed ‘its lulling charities’, Britten has the singer extend the word 'lulling' over a long, undulating, descending chain of notes while the strings droop in discrete little sighs underneath, just like the feeling of sinking one's head into the pillow and relaxing; and then, typically, the singer wakes up, wracked with anxiety about the ‘many woes’ of the day, before relievedly dropping off to sleep again in a very characteristic Britten way – the singer sings the same note repeatedly (‘seal the hushed Casket of my soul’) while the harmony shifts and changes beneath him, wafting him off to dreamland.

The Serenade helped consolidate Britten’s reputation at home, but he and Pears spent most of WWII in America and by the end of the war, they were anxious to return to the home country. They knew that they had to come back with something special. In an LA bookshop, Pears picked up a book of poems by the English writer George Crabbe (1754-1832). It would become the source of Britten's most famous opera.

Peter Grimes, Op 33 (1945)

Crabbe's The Borough, the book Pears found, is an unsentimental portrait of a rural English fishing village, and the Peter Grimes section, Letter XXII, is about a cruel fisherman who the townsfolk suspect of killing his own apprentices, or at any rate of failing to prevent their deaths. The story captured Britten and Pears’ imagination, but as often happens, the story they wanted to tell wasn’t quite Crabbe’s. They saw Grimes as a misunderstood dreamer, a violent man but one who was open to perceptions and dreams that the staid village folk had no access to.

Britten, Pears and their librettist Montagu Slater used Crabbe’s poem to create a basically simple story. Peter Grimes is a fisherman who, at the beginning, is seen answering for the death of his apprentice in a court. The judge rules that it was caused by 'accidental circumstances' but it's clear that most people don't trust Grimes, the only exceptions being the local schoolteacher, Ellen Orford; a retired fisherman, the wise and tolerant Balstrode; and the apothecary Ned Keene. Grimes and Ellen plan to marry, but he won't do it yet, because he believes that nobody in the town will accept him until he's earned enough money to set up a household. Over the course of the opera Grimes gets a new apprentice, but the boy hasn't been working long before Ellen discovers a bruise on his neck. When she confronts Grimes about it, he loses his temper and hits her. The villagers become determined to find out what's going on with Grimes, and form a mob. Grimes takes the apprentice to his clifftop hut, but when he hears the mob calling his name he urges the boy to hurry down the cliff steps to their boat, because there's a shoal of fish he wants to catch as soon as possible. Going down the cliff, the boy falls and is killed. Grimes leaves, and the villagers find nothing, but days later, the boy's sweater washes ashore and the villagers form another mob, this time looking for vengeance. In the most famous scene in the opera, Grimes enters alone and sings by himself; his sense of persecution has driven him mad. Ellen and Balstrode find him, and when it's clear that there's no hope for him, Balstrode urges Grimes to take his boat out on the sea and sink it. Grimes does so, and the next morning it's like nothing has happened; rumours of a boat sinking are dismissed, and the village gets on with its life.

A cheery little tale, then – persecution, child abuse, witch-hunts and suicide in a grubby fishing village on the North Sea. It may seem unbelievable, but when Peter Grimes was first performed in London in 1945, it was a massive hit. A London bus conductor was heard to shout ‘Any more for Peter Grimes, the sadistic fisherman!’ Peter Grimes marks a major leap forward in Britten’s mastery of writing dramatic music, but from a composer so often associated with Britishness, it’s a work that asks serious questions about our ideas of home and locality.

The heart of the opera is Act 3 Scene 2, the so-called mad scene, an extended and fractured aria for tenor, accompanied by the offstage chorus calling Peter's name and a recurrent foghorn motif played on the tuba. Like all good mad scenes, it's not just incoherent babble but is cunningly structured. It's not even accurate to call Peter 'mad', because he's not so much detached from reality as painfully over-aware of it. If you experience Act 3 Scene 2 in isolation, without having watched or listened to the rest of the opera, you miss a lot of what's going on in it; Peter is recapitulating a lot of the themes and motifs from earlier in the piece.

One of Peter’s first lines is 'What is home?'. Earlier on, when Balstrode asked him why he didn't join a merchant ship to make his fortune, Peter's reply was that he still considered the village to be home, but the story shows that his fellow townsfolk don't feel the same way, and this aria shows us Peter finally absorbing that lesson. In the course of the aria, he first of all tries to justify the deaths of his apprentices ('The first one died, just died …') but as he goes on, it's clear that on some level he's come to blame himself, and maybe not without reason. The crowd keeps calling his name, and he dreams of confronting them and even being punished by them, with his desperate bellow of 'Come on! Land me!', as if he were one of the fish he works so hard to catch. But that doesn't work, either. He fantasises that Ellen is there, but all he can do is remember how they last parted, and how he hit her in the face. The crowd's chanting of his name grows in intensity, and it turns into a battle: first he tries to defy them, then to reject them, then he looks to the sea itself for help ('Old Davy Jones shall answer: Come home!'), but the crowd's cries reach a climax and defeat him, and in a stunning reversal he's reduced to crying his own name back at them, over and over again. At this point Ellen and Balstrode have entered, and witness his mental and emotional collapse.

After that, he has just one more moment of lucidity, but it’s chilling. All through the scene, the chorus has been battering Peter like the voice of his conscience, until with their increasingly insistent singing of his name, they finally overpower him. In the ensuing silence Ellen asks him to come home, but the stage directions say he ‘does not notice her’. Then the voices return, still calling his name but this time in a soothing, lullaby-ish way, rocking gently between the male voices calling his first name ‘Peter’ and the female voices calling ‘Gri-imes’, and it's over this cyclical, lulling backdrop that Peter sings his last mini-aria, ‘What harbour shelters peace’. It calls back to a scene much earlier, when he and Ellen were planning their life together one day, and he was imagining a place where he’d finally be free of suspicion. But it's no good. The music shows us that Peter has finally accepted the condemnation that the villagers have spent the opera throwing at him: home is where he's the bad guy, and the chilling thing is that he sounds not so much defeated as relieved. Then the music dies out completely, and Balstrode tells Peter, speaking rather than singing, to take the boat out and sink it.

That's the dramatic climax of Peter Grimes: a moment with no music at all, in which the main character is advised by his closest friend to kill himself. A story that looked flat and dour turns out to be rich in hope, longing, terror, unexpected comedy and ultimate tragedy. Peter Grimes alone would probably have established Britten as one of Britain's leading composers, except that he went on to write eight more operas, including at least four masterpieces: Billy Budd (1951), A Midsummer Night's Dream (1960), Death in Venice (1973) and the one some people consider the greatest of all, The Turn of the Screw (1954).

War Requiem, Op 66 (1962)

Britten was perhaps the most literate composer ever, in that great writing didn’t cramp his imagination but set it free. Many of his greatest works are settings of poetry and prose by the likes of Shakespeare, Jonson, Donne, Smart, Blake, Hölderlin, Burns, Keats, Rimbaud, Melville, Henry James, Hardy, TS Eliot and WH Auden. Talk about taste in reading. His most famous work is also a setting of classic literature, and a public work that he used to serve a private purpose.

Like many industrial cities in the UK, Coventry was heavily bombed during WWII and after an especially heavy raid in 1940, the resulting firestorm gutted its 14th century cathedral. After the war, there was a competition to build a new cathedral. While it was being built, Britten was asked if he'd like to write some music for the consecration.

The result was the War Requiem, his biggest public statement. He scored it for multiple ensembles: a chorus of boys accompanied by an organ; a symphony orchestra with a full chorus and a solo soprano; and a chamber orchestra with two singers, a tenor and a baritone. He took the Latin text of the Requiem mass and distributed it between the boy chorus, the full chorus and the soprano, and he gave the tenor and the baritone settings of poems by the WWI poet Wilfred Owen.

Most war memorials try to make it seem like the sacrifice was worthwhile. Britten had zero interest in suggesting that those who’d died had died nobly, in the service of some great abstraction like country or God or freedom. He was a lifelong pacifist, he was determined that the War Requiem would reflect his convictions, and so the use of Owen’s poetry was a masterstroke.

Owen was almost the archetypal WWI soldier-poet. He went to war expecting it to be gallant and wonderful but when he realised that it was a hell of mud, shrapnel and mutilation, he was honest enough to say so, in his poetry and letters – and yet, after spending time in Craiglockhart with what we now would call post-traumatic stress disorder, he returned to the Western Front and won a Military Cross for bravery before being killed only a week before the signing of the armistice. Owen’s main feelings about the war were a combination of disgust at the hypocrisy of the warmongers, and pity for the dead and wounded soldiers. The Latin mass, by contrast, is concerned with humanity in general, not with individuals.

As a result, the War Requiem ripples with irony. It’s in the music itself. The offstage chorus of boys, which in some ways represent the point of view of heaven, is often accompanied by bells tolling in the most ambiguous of all the harmonies, the tritone, making them sound chilly and uninvolved. The full chorus and the soprano stand in for the civilian masses, sometimes terrified, sometimes pious, but either way shoved one way and another by the music. The tenors sing the sentiments of the soldiers: weary, sardonic, angry and pitying. The climax of the War Requiem is a setting of Owen’s poem ‘Strange Meeting’, in which a British soldier escapes from the battle down ‘some profound dull tunnel’ and finds himself among the enemy dead, whereupon one of the dead men rises and addresses him. The German turns out to be a man the British soldier killed, but now he offers forgiveness and comradeship with the invitation ‘Let us sleep now …’ On this, the tenors, the chorus and the orchestra rise in a wonderfully tender, almost erotic swirl of melody, a vision of ease and reconciliation after the previous ninety minutes’ horror of war. But then the distant chorus of boys returns, with its by-now-heavily-ironic refrain of ‘Requiem aeternam dona eis domine’, ‘Give them eternal rest, Lord’. The larger ensemble tries to win out, but wars never end. The boys have the last word; the Requiem ends in quietness and doubt, with an unresolved tritone still echoing.

The War Requiem is not background music. You put it on to listen to it. Britten made a great public statement out of his private convictions, and the result is a million miles away from the kind of cheerful but mindless jingoism you sometimes get at a Last Night of the Proms. Maybe that’s why Derek Jarman made a movie of it.

Britten wrote much else that was as great, in different ways. Apart from the operas mentioned above, there are the song cycles: 'Winter Words', 'The Songs and Sonnets of John Donne' and 'Sechs Hölderlin-Fragmente’ are outstanding. There’s the sparky and inventive Young Person’s Guide to the Orchestra, the menacing Nocturnal for solo guitar, the charming Noye’s Fludde, a mini-opera written for a chorus of children. Like so many great composers, there’s more than you could ever hope to take in. Britten believed that composers needed to be useful to society, yet he was often at odds with his own society. It’s a wonder that he wrote great music at all, but then it's a wonder that anyone does.

BBC Symphony Orchestra - Britten 100

Peter Grimes - Jon Vickers