So what could possibly have gone wrong?

As it turns out, almost everything. Two years ago, he nearly quit as the managing director as debts and bank pressure looked set to drive the company under. "I think we were groundbreaking," he says with a wry grin. "Because we experienced toxic debt 18 months before the rest of the world."

Astonishingly, the garrulous Liverpudlian managed to keep his state of near collapse from the media industry and most of the staff, despite the fact that problems arose almost as soon as Mulville and his business partner - and now ex-wife - Denise O'Donoghue sold 45% of Hat Trick for £23m. "The night Denise and I signed the deal we did have a moment when we felt really, really proud of ourselves," Mulville recalls.

But the pair had started looking around for acquisitions in 2003 to swell their empire - August Equity, like all venture capitalists, wanted to grow the company then float at a profit. They spoke to Eileen Gallagher, the founder of the drama indie Shed Productions. She thought adding Hat Trick and Shed together would be like 1+1 making 3. Until she went through their books. She found that the money paid out to Denise and Jimmy was now owed by Hat Trick until the hoped-for sale. It was like taking out a mortgage on the company to pay off the mortgage on their home. "Eileen said: 'I've just seen you've got this socking great debt at the heart of your business - why would I want to take that on?'" Mulville says.

"So the scales fell from our eyes and we realised we weren't going to be able to do the acquisitions so we'd have to grow the company organically."

These plans fell foul of commissioners. "[The Hat Trick shows] Room 101 and The Kumars at No 42 got cancelled and Bodies was scandalously cancelled by the BBC despite being a big hit. Our earnings went down by about 30-40%. Whose Line Is It Anyway in America was accounting for 25%. That came off air. Suddenly earnings were halved, and our debts were still there."

The next four years were chaotic. The Worst Week of My Life came on air then went off. The Kumars was a dead cert commission for Fox in the US until the network president hated the host and cancelled it. Programmes slipped from one financial year to the next because lead actors took six months off to find themselves, says Mulville. At one board meeting he explained the latest setback to the venture capitalists and a banker croaked: "This is a f**king frightening business, isn't it?"

Although its existing shows were profitable, it was hard to pay off the £23m debt and the banks started applying pressure when Hat Trick breached a covenant. In 2007, Mulville threatened to walk - warning that the company might collapse if he did so. "It was horrible going into work," he explains. "The guy from Barclays's debt support unit would come in and look at our development board and say: 'Will this show work?' I'd say: 'I don't know.' He'd say: 'What formula can you use?' I'd say: 'There is no formula.' I was thinking, 'How do we get out of this?' because it seemed intractable. The debt was just too big. And I realised this business shouldn't get involved with purely financial institutions."

Salvation eventually came from an unexpected quarter. David Young, the inventor of The Weakest Link and a former Hat Trick runner, sold his production company, 12 Yards, in 2007 to ITV for £35m. It was a 50/50 joint venture with Hat Trick and with the proceeds of the sale, Mulville decided to buy back most of the shares from August Equity. Last month August left the board. "That's why I'm able to talk about it now," he says.

August plans to reduce its 45% stake over the next few months although the contract stipulating terms is still being signed. Once this process is over, Mulville, O'Donoghue, the new chief operating officer, Debbie Manners, and other senior management will be the main shareholders.

Richard Green, the chairman of August Equity, says: "Jimmy is an amazingly talented TV producer constantly coming up with new ideas. We're always looking for profitable investments for our investors and looking to realise a profitable exit in the future - that's been our policy with Hat Trick."

Manners says: "I came in to help Jimmy follow his talent and stop worrying about following the money. When all of this is finished, Hat Trick will be a small, creatively owned independent again."

The team is excited about some forthcoming productions, including Krod Mandoon, coming soon to BBC2 and starring Matt Lucas and Sean Maguire.

After graduating from Cambridge, Mulville script-edited and produced Alas Smith and Jones and starred in the cult 80s sketch show Who Dares Wins as well as the sitcom Chelmsford 123. He founded Hat Trick in 1986 to produce Chelmsford when it was a radio show with his comedy partner McGrath and O'Donoghue, building the company into a comedy powerhouse.

In the process, however, Mulville had to seek help for cocaine and alcohol addictions - "I've been in Alcoholics Anonymous for 20 years," he says. He married for the third time in 1999 but still credits O'Donoghue, who left Hat Trick in 2005, with winning contract battles with broadcasters that kept various programme rights for the company.

"When we first got going it was like we were the feudal serfs at the gate of the manor house," he says. "Every Thursday he'd pop out and dispense largesse by giving you a commission. You'd tug your forelock, then try and scrape a bit of profit off the back of it. Those days are gone because the manor house is mortgaged to the hilt - he ain't got no largesse. So these days you have to bring money to the table."

With 80% of the UK shows on US screens coming from independent production companies, he's doing deals with American networks to provide this cash - "going to the broadcasters with solutions", he calls it. He is, however, exasperated with the BBC. "The BBC are asking for big cuts in programme budgets but because the commercial broadcasters are in such trouble they seem to be the only beast in the jungle of any significant size," he grimaces.

"They've got to behave themselves a bit. The most over-used cliche of the moment is 'in the current climate'. The BBC are like undertakers now - 'it's the current climate'. Well, no, your current climate is exactly the same. You get £3.5bn a year. Your climate is sunny. You're in the Mediterranean. You're not in the frozen wastes of ITV. So they need to shape up a bit, especially when they're asking people for cuts in the budgets of hit programmes."

He freely admits that he wouldn't be where he was today without the BBC's patronage - his first job in radio comedy gave him room to learn and the bulk of his shows have been on BBC networks. "The BBC at the moment is bingeing on fear," he says. "They need to remind themselves that they are the greatest broadcasting institution in the world. I think it's an odd combination of low self-esteem and enormous self-importance. That is the classic self-absorption of the addict. What worries me is that it's now endemic and even the foot soldiers are running around with compliance forms when they should be running around with programme ideas."