It’s 10.05am in Detroit, and over a transatlantic phone line Martha Reeves is extolling the virtues of 1960s Motown’s in-house band The Funk Brothers. ‘Listening to the radio today, there’s a lot of music that is not made by musicians,’ she grumbles. ‘There’s maybe one guy who’s on a synthesiser or a beatbox that has the same beat as the last record you heard on the radio. You get none of their personality. The Funk Brothers were vital to Motown’s success.’

Then, not for the last time during our nearly hour-long conversation (I’d requested half that amount of time), the 72-year-old’s memory is tripped and she launches into what typically will be a well-practised but nevertheless enthralling anecdote from the good old days when Motown possessed arguably the greatest stable of pop musicians ever assembled.

Reeves regales me with remarkable reminiscences, such as the first day an 11-year-old Stevland Hardaway Morris walked into Motown’s Hitsville USA building and proceeded to play everything in the office, right down to a wastepaper bin, immediately earning himself the alias ‘Little Stevie Wonder’. And then there was the moment a hitherto shy session drummer called Marvin Gaye slipped off his ever-present hat and shades to reveal just how damn handsome he was.

But Reeves gets promptly interrupted. ‘Sorry, that’s my phone,’ she apologises, as an instantly identifiable amalgam of soaring brass, rolling drum pick-ups and full-blooded, velveteen singing begins to blare in the background through a tinny mobile: ‘Calling out around the world/are you ready for a brand new beat?’ She laughs. ‘My son put that on there! Even my ringtone has The Funk Brothers playing on it!’

As the lead singer of Martha and The Vandellas (her surname was added in 1967), Reeves – born third in an Alabaman family of 11 children – gave Motown over a dozen hits. Her career there began at 21 with a business card from A&R man William Stevenson following a club show. Naively not realising that auditions were only held on particular days, she wandered into Hitsville the next morning only for an overworked Stevenson to leave her answering phones. Proving so adept at it, she was instead hired as a secretary.

When I innocently ask after this oft-repeated quirk of her bio, Reeves quickly reveals a more combative side of her generally good-natured temperament: one that hints at why she had a crack at politics as a Detroit council member from 2005 to 2009. ‘I did not go there to be a secretary,’ she snaps. ‘That’s the first thing people want to call me: a secretary!’

Such fighting spirit saw Reeves quickly graduate from secretary to recording artist in her own right, scoring her first hit in 1963 with ‘Come and Get These Memories’. Timeless classics followed, from ‘(Your Love is Like A) Heat Wave’ to ‘Jimmy Mack’, ‘Nowhere to Run’ and, of course, ‘Dancing in the Street’. Rattled off in just two takes, as Reeves recalls, the latter song is regarded today as the Motown anthem, and has been covered by everyone from David Bowie and Mick Jagger to Van Halen. ‘There’s nothing like the original,’ she swaggers.

After a few rough years, Reeves became a born-again Christian in 1977 and for a long time concentrated on gospel music. Her faith throws up some barriers when it comes to discussing less happy events: her drug problems, her side-lining at Motown in favour of Diana Ross and The Supremes and a breakdown in relations with the label following its relocation to LA in 1972, leading eventually to her suing Motown for unpaid royalties in 1983. When I ask whether she carries any grudges or regrets, I’m politely stonewalled on grounds of ‘divine order’.

‘There were times when you were hot, and there were times when you were not,’ she elucidates. ‘Trials and tribulations only strengthen us. I wouldn’t have done anything different and life is perfect.’

It’s hard not to be swept up in her devout optimism, the same joyful fervour which makes her gigs such life-affirming experiences. Reeves’ voice is far from the powerful instrument it once was, but driven by sheer force of personality, her live performances are remarkable celebrations of the Motown spirit – romance, inclusivity, exuberance – as much as the music itself.

A lot of international artists claim to love Scotland, but with Reeves it’s indisputably true. She first came here in 1965 supporting Georgie Fame on the debut UK Motown Review tour, and has returned countless times since (‘Jimmy Mack’ is often mistaken for a Scotsman, she notes). Reeves has ‘a multitude of great friends’ in Scotland, in particular two super-fans called James and Harry. After her last Scottish gig at Glasgow’s Òran Mór in December, she celebrated Christmas with them in the village of Sorn, between the local church and pub. ‘My relationship grows more and more for Scotland. I find it a very beautiful place: the hills and the green grass all year round are amazing.’

I had planned on asking Reeves whether, after 50 years of performing the likes of ‘Heat Wave’ and ‘Dancing in the Street’, she hasn’t wearied of them. But her ringtone has already answered that. ‘The only time I’ve felt a little embarrassed by it was in church. The phone went off and everybody looked around. I had to keep myself from getting up and dancing.’

And then suddenly she’s off with another anecdote, gradually winding her way towards a typically verbose but heart-warming conclusion. ‘When we hear the music,’ she says thoughtfully, as if beginning a sermon, ‘there’s a happiness and a youth there: it inspires me and I’ve been told it inspires a multitude of people who have purchased the Motown sound and can identify with the good times that it represents. So I can feel as young as I felt when I recorded it. Every song I ever sang on Motown is one I delighted in and one that I am proud of. Proud of my performance, proud of the combination of musicians and singers, the producers and the writers and everyone who collected together to record these masterpieces that we hold title to and are privileged to have.’ Amen to that.

Martha Reeves and The Vandellas, Assembly Rooms, George Street, 0844 693 3008, 6 & 7 Aug, 9.30pm, £20.