Drawn to Dulux

He takes me up to the attic studio in the gallery-cum-shop he's just opened in Sheffield, where he was born and which inspires him, in a downbeat sort of way. He's steeped in the Sheffield of the '60s, '70s and '80s: the pre-regeneration city, in all its working class splendour, its proud, blunt radicalism, its post-industrial nostalgia. It's the obsessive theme of his phenomenally successful, astonishingly prolific work. Successful? Exhibitions in London and New York. Work taken up by Noel Gallagher, Richard Hawley, the Arctic Monkeys and fashion designer Paul Smith. Look at the snapshots of his exhibition openings. Here he is with Jarvis. There he is with Damien. Not bad for an artist who spent five years working a 6am shift at Tesco sorting out home shopping orders.

Back to Dulux. "The pigment in emulsion works well because my style's quite flat," he says, halfway up the steep second staircase. "The overriding factor is the colour palette. I can get it mixed to order." Stacked on the studio shelves are tin after tin of emulsion with hand-written labels that hint at his preoccupations: Pub Seat Red, Summer Sky, British Sea (more sludgy than sunny), Whippet (there's a whopper whippet, looking rather worried, painted on the gallery front).

McKee goes for scenes from everyday life on the day before yesterday, "before shell suits and flat-screen TVs". There are sideburned men in pubs and clubs, beehived, headscarfed women in bingo halls, lads at football matches, playing crazy golf on seaside caravan holidays, tapping their feet to jukeboxes or strumming lonely guitars in small bedrooms. Most of them live up Memory Lane.

They flock to the indoor markets or the Crucible for the snooker, or the Leadmill or the Limit for the bands. They gawp at the fish in the giant aquarium set into the wall of "The Hole in the Road", a long-gone city-centre underpass. I say – and I don't often – that I once interviewed the man who changed the aquarium water. McKee's eyes sparkle with fascination as though I've said I once interviewed Stanley Matthews or Christine Keeler.

His people are boldly stylised and tend not to have eyes. Easier to see their souls

without them, he says. Sometimes a horizontal line stands in for the full monty of eyes, eyebrows and nose. And they don't always have mouths. They could have ended up looking blank, literally faceless, but they have a curious, often vulnerable, expressivity. And they're cartoon-like: McKee has been sports cartoonist of the Sheffield Telegraph, the city's weekly newspaper, for the best part of two decades."Cartoons are a language I grew up with," he says. "Beano and Dandy. My dad would come in off the night shift and throw me the Daily Mirror and I'd try to draw Andy Capp."

He looks as though he could still belong to that era, or earlier (he was born in 1966 but his frame of reference is all-encompassing post-war). He wears Forties-style waistcoats, slicks his hair back in a Fifties quiff, looks the way his dad might have looked on his way to the steelworks where he was on the shopfloor. Did his mother work? "She put the cherries on top of Bakewell tarts at Gunstones bakery."

They lived in a two-up two-down terrace, in the city's industrial East End. "On Sunny Street – nice names for soot-ridden streets with smog." His father was in a group called the Accordion Serenaders, who toured the clubs. McKee points out a photograph of them, looking very spruce, on the wall of the gallery back room where we're now sitting.

We're at a table recreating a kitchen scene from the 1960s, with a big red plastic ketchup tomato and a bottle of Henderson's Relish, a legendary local answer to Worcester sauce. The wall is a potted history of McKee's life, personality and influences – a Sheffield Wednesday pennant, pictures of Tin Tin, a melancholy Edward Hopper postcard, a framed Sheffield dessert knife. "I wanted to create a living McKee painting," he says. It's the sort of kitchen he knew when the family moved to a council house on an estate which "looked like Butlins without the fun". He didn't shine at school. "I was a very poor learner, couldn't concentrate. I wanted to write and tell stories but I couldn't string a sentence together without 40,000 spelling mistakes. But I was good at art and pottery."

He left school with no qualifications after one year in the sixth form and got a job in a kitchen door factory popping air bubbles in pre-moulded foam. "Pricking air," he calls it. "It made me determined not to do that for the rest of my life, but it gave me 60 a week and I could buy a keyboard..." He set up a band, "thought we were going to take over the world and become bigger than The Beatles", but they didn't and he got a job in an HMV shop, selling other peoples' records instead. Now, though, as if in homage to his father's vintage music-making, he's in a ukelele band called the Everly Pregnant Brothers. He went to night school, couldn't get into art college, wrote gags for greetings cards, sent some cartoons off on spec to the Sheffield Telegraph, and was taken on to do one every week.

"I only nearly missed the deadline once. I was on holiday in Devon in a caravan and couldn't find a postbox to post it back to Sheffield. But I eventually did."

He started painting, had exhibitions in pubs, and got a big break when Noel Gallagher commissioned him to design the posters for an Oasis tour. The celebrities kept coming, most recently Paul Smith, who staged an exhibition of McKee pictures at his Tokyo store. So much work, so many commissions. Does he paint obsessively, all hours God sends? "An Indian philosopher said: 'If you can find something you enjoy doing, you'll never work again'."

And now the gallery, on Sharrow Vale Road, in the quietly boho-ish Hunters Bar area of Sheffield. It's called A Month of Sundays. Why? "I like the wistfulness of the phrase," he says. "It's about something that will never happen. It's a good phrase for a working class person, whether it's about winning the lottery or paying off the hire purchase on a settee." And does it reflect his own early doubts about his career? "Well, yes, at first it seemed I'd never make a career out of art." He still seems a bit bemused by success.

The gallery has its own jukebox and, of course, pictures: originals from 800 to 2,500, prints at 120, an original sketch of an ice cream van at 1,800. It's an antidote to what he calls "white-walled galleries that can be intimidating, places where people feel they have to pass a test to go in in the first place".

It all chimes in with his celebration of working class life and Sheffield. So how does he define a Sheffielder? "You're

never going to get a serious conclusion from anyone in Sheffield. We're

self-deprecating, not great flag-wavers, don't take ourselves too seriously. But Sheffield fights its own corner. We're independently-minded people."

And they paint with Dulux.