Agent provocateur: BBC's head of drama plans plenty of sex and the return of Tom Stoppard

Ben Stephenson is shaking things up at the corporation

A season of sex is being planned by the BBC. Such an idea inevitably risks the wrath of moral guardians, as well as the snorts of critics who might think it sensationalist and unoriginal. So if you're going to do it, make sure you have the hot writer of the moment signed up for the project.

Ben Stephenson, the BBC's youthful head of drama commissioning, realises this. He has engaged Billy Ivory, a former Nottingham binman, to dramatise the works of DH Lawrence, the greatest East Midlands writer of them all.

Ivory – who is already being compared to the great Nottingham working-class author Alan Sillitoe – will bring his personal interpretations of The Rainbow and Women in Love to BBC4 next year, as the centrepiece of a season devoted to love and sex. The two 90-minute productions will be placed in the schedule alongside Amanda Coe's adaptation of John Braine's Fifties novel Room at the Top and a series of documentaries that examine aspects of intimacy and romance in the 20th century.

"Billy Ivory is a real Lawrencian – if that's a word, I may have made that up," says Stephenson in his office at Television Centre in London. "I think the work is incredibly faithful to the spirit of Lawrence, but it's quite a different and bold way of doing an adaptation and very much Ivory's take on it. He's one of the best writers in the country and I think he's going to have an amazing year."

Ivory's highly anticipated debut feature film, Made in Dagenham, which is set in the Sixties, will shortly be released by BBC Films. His Lawrence dramas will star Rosamund Pike and Rachael Stirling.

This sex season, says Stephenson, is about reappraising the approach to drama on BBC4, a channel that has built a reputation for broadcasting biopic stories of British cultural figures from Kenneth Williams to Gracie Fields. "Inevitably it's time for us to ring the changes," he says of the shift in direction.

He has even bigger plans for BBC2. There seem to be wider concerns at the corporation that the channel is not punching its weight, and it has been allocated a greater share of the drama budget in order to redress a perceived imbalance in resources. "One of my big things over the next few years is giving BBC2 a reputation in drama," says Stephenson. "Therefore we've got to have pieces of the highest possible calibre that have real filmic ambition, that have big, intelligent stories to tell."

Sir Tom Stoppard and Alan Bleasdale, both long missing from television, are producing new work for BBC2. Bleasdale, who has not written for the BBC in 24 years, is dramatising the story of the Laconia, a British ship that was sunk in the Second World War. Sir Tom has not made a drama for British television in 20 years, and securing his talents is a major coup.

Stephenson says that the need to redefine drama on BBC2 is partly a result of the changing expectations of audiences on BBC1: "The interesting thing that has happened is that drama that five years ago would have been on BBC2 is now sitting on BBC1." Major pieces such as the Iraq drama Occupation and the Caribbean immigration story Small Island (based on Andrea Levy's book) have been claimed by the corporation's flagship channel. "The depth of those narratives, and the grittiness, was natural to BBC2; [but] what's happened is that on BBC1 we are now delivering audiences heavyweight subject matter by complex writers, and the audience is telling us that's exactly what they want."

He has had to rethink BBC2's purpose in drama. "We've had to say, 'Where is the story moving for BBC2?' and I think what we've found is that there's a big gap in the market for drama that has an alternative view on the world." This switch in emphasis will begin this autumn with a slate of "complex pieces", including Shadow Line, which stars Christopher Eccleston and Sir Antony Sher. Chiwetel Ejiofor is breaking off from his Hollywood commitments to take part in the crime series written by Hugo Blick (a writer better known for comedy such as Marion and Geoff). Stephenson claims things will get really interesting on BBC2 in 2011, with a string of six-part series: "Next year is the dawning of what I hope will be a really cool, new BBC2."

He has commissioned not just stellar names such as Stoppard but talents such as Abi Morgan (the writer of TV drama Sex Traffic and the feature film Brick Lane), who is scripting her first multi-part series, The Hour, for broadcast later this year. "It's a love triangle against the backdrop of the birth of broadcast news in the 1950s in London. That is an alternative piece of history and an alternative way of telling a love story, and absolutely belongs on BBC2." He denies that the Fifties setting is an attempt to piggyback the cult success of Mad Men. "The only thing it's got in common is that it's set in the Fifties – beyond the fact that it's brilliant."

Similarly, BBC3's upcoming lesbian drama Lip Service has little in common with the American show The L Word, aside from the sexual orientation of the star characters.

"It's great fun, and I really think you want to spend time with these characters," he says. "It's also a really brilliant portrayal of Glasgow. It makes it feel like the modern city it is, and makes you want to live there. More importantly, it's a writer's personal take on love, sex, relationships and sexuality."

Asked what type of drama is no longer deemed appropriate for BBC1 following this change around, Stephenson – who was appointed nearly two years ago and is still only 33 – is at pains not to say anything that might reflect badly on his predecessors, but settles for: "things that lack complexity".

The period "bonnet" dramas for which the BBC is world-famous will become less of a priority. "I think period drama is a really important part of what the BBC does, [but] a really tiny part. I think it's something like 7 per cent," he says. "The majority of what we will make is contemporary and I think we will be making less period drama than we have made."

Scotland will become increasingly prominent as a backdrop. As well as hosting BBC3's Lip Service, Glasgow is the location for the BBC1 drama Single Father, which stars David Tennant and examines the dilemmas of a suddenly widowed father of two in his search for a new love. Edinburgh, meanwhile, is the setting for Young James, based on the diaries of James Herriot, and Case Histories, based on Kate Atkinson's stories of a private eye. "I'd like to look back in three years and feel that we've got a greater diversity of drama that reflects different places," says Stephenson.

Such ambition is rare in a media industry under extreme financial restraints. The corporation's head of drama commissioning realises he is in a privileged position in not having to deliver work that targets an advertising- driven demographic. That's also an advantage that he is ready to exploit ruthlessly to ensure that the best writers give their prized work to one of the BBC's four channels. "We have that ability not to be marching to a commercial drumbeat" – that's his pitch.