Eric, Ernie... and Victoria

It's a somewhat unsettling thought for someone of my generation – the middle-aged, not wanting to put too fine a point on it – that young people may well have never heard of Morecambe and Wise. Or only have the vaguest idea of what they were about. "People under 40 don't really know who they are unless they've seen them on YouTube," reckons Victoria Wood when we meet up to discuss her latest project, Eric and Ernie, about the early partnership of Eric Morecambe and Ernie Wise – long before they became national institutions and their Christmas specials were attracting 28 million TV viewers.

But even among those of us who do know Eric and Ernie, recalling their famous hopping and skipping dance "Bring Me Sunshine", larking around with Glenda Jackson and all that, few will know how Morecambe and Wise first met, or of their long years of struggle before they became the nation's favourite entertainers. Or indeed the fact that they once went under the name of Bartholomew & Wiseman, "like a firm of solicitors", as someone says in Victoria Wood's cracking new drama about the pair.

"They didn't emerge as middle-aged men," says Wood. "We may think of Morecambe and Wise as that brilliant and much-loved double act but I've always thought that a film about their days as child performers in variety, and their struggles to establish themselves, would make a fantastic story."

Ernie Wise (né Wiseman) was already a child star – billed as "Britain's Mickey Rooney" – when he met the 13-year-old Eric Bartholomew on the touring juvenile variety show, Youth Takes a Bow. "Ernie was the headline... he was the star at that point, and Eric was somewhere right down the bottom on the bill," says Wood.

Her drama follows the duo's progress from 1939 until 1954, when their first BBC TV series, Running Wild, bombed. It was a critical failure that had one TV reviewer describing television as (prematurely as it turned out) "the box they buried Morecambe & Wise in".

Wood is plainly dressed in grey sweatshirt and jeans today, an executive producer at work. She first had the idea for the drama about seven years ago, she tells me. With the BBC keen for her to lend her star-power to what was going to be largely unknown cast, she ended up playing Eric Morecambe's mother, the formidable Sadie Bartholomew, the housewife who first saw the potential in the double act.

"I don't like acting, or wearing the costumes, I don't like wearing wigs, I'd rather not do it at all," says Wood. "I think it was part of the deal that I should be in it. I'd rather take a back seat." But thankfully she is on screen, for Wood's Sadie knits the story together beautifully. Wood may not particularly enjoy the business that goes with it, but, being primarily thought of as a comedian, she is an underrated actor (although not entirely – she won a Bafta and an Emmy in 2006 for her performance in Housewife, 49).

She's no mean writer either, having scripted Housewife, 49, as well as the award-winning Pat and Margaret, on top of her solo stage and TV material, and the hit sitcom Dinnerladies, although she chose to forego the writing duties on Eric and Ernie, hiring Peter Bowker (Blackpool, Desperate Romantics) instead.

"Pete Bowker has probably read everything ever written about Morecambe and Wise; one of his children is called Eric, he's an avid Morecambe and Wise fan, so he knew a lot of stuff already," says Wood, adding that she included one or two gags herself. "I mean he can write his own gags but sometimes I couldn't help myself."

And the resulting drama is warm and very funny – not at all like the gloomy BBC4 biopics about Kenneth Williams and the stars of Steptoe and Son. "It's not one of those dark The Curse of Comedy dramas," she says. "Kenneth Williams... we know he was tortured because we've got the evidence in his diaries. Steptoe and Son, that's not so interesting... one of them is gay. Our story is more interesting.

"What's special about Morecambe and Wise was their success was based on a genuine friendship. Ernie always found Eric funny and Eric's ribbing of Ernie is coming from an affectionate place. Eric's wife said to me that whenever she would go to see him and walk past the dressing room, she could always hear them laughing."

Wood visited Joan Morecambe and her son Gary, as well as Ernie's widow, Doreen Wise, and they were invited on set. "Both women were incredibly helpful because they knew Sadie well," she says. "And Doreen has a fantastic archive of photographs from when Ernie was a little boy appearing in shows in Leeds and Bradford." These early photographs came in handy for the "nightmare" casting process – a total of six Erics and Ernies were needed as the comedians aged between 13 and 29. "The Ernies all had to be able to dance, the Erics all had to be able to dance enough. We had a nice lot of Ernies, good singing and dancing boys. It was harder to get that Eric quality."

They got there in the end however, and "that Eric quality" has been miraculously distilled in actor-cum-stand-up comedian Daniel Rigby. Another relative newcomer, Bryan Dick, is well cast as Ernie.

"I think we've done really well, actually," says Victoria Wood. "I think we've got people you do believe in when you see them." As Eric's father, she has cast Jim Moir – aka Vic Reeves – a performer whose double act with Bob Mortimer has often been likened to Morecambe and Wise.

It was Peter Bowker who came up with the idea of involving Eric's parents, Sadie and George, in the story. "I felt it was very much a man's story," says Wood. "So it seemed better in the hands of a male writer. But Bowker came up with the idea of involving Eric's parents."

It was Sadie who pushed Eric and Ernie together, and there's a neat, unforced scene, where, in digs together in Leeds during a wartime bombing raid, the two lads share a bed – an echo of when they would often lie in bed like an old married couple in their TV comedy sketches. Was Sadie an archetypal pushy showbiz mum?

"I think she was a very intelligent person who realised that Eric would never be happy in a dead-end job, staying in Morecambe like his father had, working for the Gas Board," says Wood. "If making people laugh is what you're good at, why not do it for a living?

"The workings of comedy interest me as a comedian. I like the high level of professionalism, and you only get to that by working, working, working for years and years and years. That's why they're so relaxed (on TV) they know they can deal with any situation, they've been through everything – just see that rapport. They are still making each other laugh after all those years."

'Eric and Ernie' is on New Year's Day at 9pm on BBC2