During an online interview a decade ago, alongside fellow Cambridge Footlighters Simon Bird and Joe Thomas, Jonny Sweet declared that writing was the part of the creative process that he most feared. Back then he was a performer of much Edinburgh Fringe renown having scooped the Best Newcomer Award in 2009 with a superb solo show after a series of successful sketch affairs with Bird and Thomas. That trio also appeared in the vastly under-rated WWI Sky sitcom Chickens (about three men who refused to fight in the trenches for very different reasons, none of them especially honourable).

But if writing was once a hellscape that Sweet was desperate to avoid, the times they have a-changed. The publication of his debut novel, The Kellerby Code, comes hot on the sharpened heels of his screenplay for Wicked Little Letters. That delightful cursefest about poisonous correspondence being dropped through letterboxes in a small Sussex village during the 1920s was, almost unbelievably, based on a true story.

Fair to say, then, that Sweet is taking to the whole writing malarkey better than he was ten years ago. ‘At that point, I was writing a radio sitcom which became Together for TV, and it was the first thing I had written on my own,’ he recalls. ‘It wasn’t about how to write ten minutes or an hour of live material, this is assembling characters and working out a plot, so it was certainly different. I have always wanted to write a book but put it off because I never felt that I had the tools. But weirdly, this book was the most pleasurable writing experience I’ve had. And also, I like a bit of time to myself. I now fear everything else.’

The Kellerby Code is a stirring romp set in the modern day but with heavy PG Wodehouse vibes as it brings together Edward Jevons (a hint in the name there of PG’s most famous butler), a man who is described at one point as ‘a doormat waiting for a house’. Edward can’t stop helping out and running errands for a sort-of friend, a vaguely pompous theatre director called Robert Pepper (one letter away from sitcom writer Robert Popper who cast Sweet in Channel 4’s I Hate You: the name, he insists, is pure coincidence).

Both men are besotted with Stanza, a bohemian who is on high alert to inherit the ostentatious country pile of Kellerby. When it’s revealed that Pepper is being blackmailed by a figure who most likely runs a gangland operation, Edward (a gentle giant with a tragic backstory) steps in to bail his ‘friend’ out but using methods which have devastating consequences (without spoiling too much, Sweet calls his debut a ‘murder farce’).

‘I want people to be on Edward’s side but also for them to think that he might well be the maddest among them,’ states Sweet. ‘I’m on his side but there are moments when you think Robert and Stanza’s worst crimes are apathy and a low-level amorality. But it’s the social architecture that Edward finds himself in that turns him into something else.’ 

The Kellerby Code is dedicated to Sweet’s parents who, it seems, were never fully certain that a career in entertainment was a serious proposition for the son they expected to excel in the legal profession. ‘My agent said the only thing that seems to calm parents down is a Radio 4 series. Well, I remember Joe and I writing sketches for a Radio 4 sketch show and we got about £16.50 each for two weeks work. But the book and the film have made it easier for them to tell people at bridge what I’m up to, rather than telling people he’s done a show about the HMS Nottingham in a corrugated iron bunker somewhere in Edinburgh. So I think they have calmed down.’
The Kellerby Code is out now published by Faber.