British TV is about to be shaken to its foundations tomorrow night as a much-anticipated one-off drama co-written by a Bradford man hits our telly screens.

Already dubbed "the sickest TV drama ever" by a national newspaper - although they hadn't seen it yet - Wedding Belles goes out on Channel 4 an hour after the watershed - and has brought writer Dean Cavanagh to national attention.

It's no surprise that the drama would have Mary Whitehouse spinning in her grave as Dean's co-writer is Irvine Welsh, author of the controversial but critically acclaimed Trainspotting (first a cult novel, then a hit film), the everyday story of junkie folk in Edinburgh's hinterlands.

Dean, who lives in Cottingley, admits that Wedding Belles "might not be for your granny". The story about four girl friends in Leith, near Edinburgh, features drug addiction, sex and suicide.

He said: "It is very raunchy in parts, but it all has context to it. Everything that happens is for a reason. There's nothing gratuitous in there. But I admit it might not be for everyone."

The outrage from the Sunday newspaper has been balanced by much more positive reactions from critics who have seen advance copies of the drama, which also gets a simultaneous DVD release.

Dean said: "Even a lot of the tabloids who were initially against it have come round and changed their minds after seeing it. We're getting great reviews from the red tops and from the critics on Newsnight Review, so we're appealing to everyone."

This is the first TV drama that Irvine Welsh has put his name to, and he and Dean are determined to do more to help shake the British television industry out of its rut.

Welsh splits his time between the US and Dublin so doesn't watch much of the UK's terrestrial output, but Dean thinks the state of the schedules is cause for concern, with cosy, undemanding, even boring TV programmes.

His view was echoed by Life On Mars actor Philip Glenister yesterday who, in a move that would have his politically incorrect copper Gene Hunt in the hit BBC series proud, took British telly by the scruff of its neck and gave it a right kicking in a dark alley when he said: "There's so much dumbing down on television. I'm fed up that every awards ceremony has a special soap category. I don't want to be a snob, but they only do it to satisfy market forces."

Dean said: "We've got an absolutely fantastic team of actresses - Shauna MacDonald, Shirley Henderson, Kathleen McDermott and Michelle Gomez - and it was great seeing them bring the story to life while we were filming in Leith.

"Everyone's said to us that it would be stupid not to do a series with the same characters, so Irvine and I are working on a pitch for that now. What it will be called and whether it will be with Channel 4 depends on a lot of things, particularly the ratings and reaction to Wedding Belles."

Wedding Belles is on Channel 4 tomorrow at 10pm.