MRS BROWN's Boys is the shock TV sitcom success of the decade.

The tale of the foul-mouthed Irish mammy, played by writer and performer Brendan O'Carroll, has become a TV hit not only in the UK and Ireland, but across the world, from Iceland to Australia.

Now, a new authorised biography of O'Carroll tells of his early life in a Dublin council house, one of 11 ­children whose mother was a former nun. O'Carroll's ­journey takes him from young offender's institution to leaving school aged 12 and working as a waiter.

The book by Herald & Times writer Brian Beacom reveals a funny but formidable character who ran his own nightclub aged 14 and went on to have a series of jobs, from farmer to window cleaner, insurance salesman and pub boss.

O'Carroll only made the breakthrough into comedy at the age of 35, after the pub he owned collapsed and he was made bankrupt.

The book also traces O'Carroll's career as a writer of the Mrs Brown books and stage plays.

The plays were a massive hit when they came to the Pavilion Theatre in Glasgow, but, after several years of big audiences, attendances had started to drop.

Beacom took Rab C Nesbitt writer Ian Pattison along to see what Mrs Brown was all about, and that night he contacted a producer in London with a view to turning the show into a sitcom.

In the biography, O'Carroll reveals he's on course to make more than £50 million in the next five years. Thanks to the success of the TV show, his live tours are sell-outs and he has progressed from theatres to arenas.

"Brendan's story is all the more poignant because he has been bankrupt twice in his life," says Beacom. "But what he had, which most people don't possess, is not just an acute writing talent and comedy bones, he's also one of the most single-minded determined people I've ever met."

Beacom acknowledges Mrs Brown's Boys is not everyone's pint of Guinness. "Some critics hate it," he says. "It's regarded as too old-fashioned, too predictable. Yet, others say it's warm, funny and nostalgic, harking back to the 1960s and family-based storylines."

Whatever the critics say, O'Carroll could care less. "We're not pleasing the ­critics," he says of his show. "And if the critics could write what I write, they wouldn't be critics."

l The Real Mrs Brown: Brendan O'Carroll, by Brian Beacom, is published on September 26 by Hodder & Stoughton, £20.