It is a battle of the ballcocks, a fight to the death over the U-bends of the rich and famous. The weapon of choice, however, is not the monkey wrench, or even the sink plunger, but the High Court writ.

Charlie Mullins, Britain’s richest plumber and almost certainly the only one to drive a Bentley convertible, has begun a £1 million legal claim against a rival business that he has accused of industrial espionage.

His company, Pimlico Plumbers, which numbers among its clients celebrities such as Keira Knightley, Hugh Grant, Daniel Craig and Dame Helen Mirren, is charging a recently established competitor, Service Corps, with stealing confidential information and trying to poach customers.

And his rival in London is no ordinary fixer of leaky taps and blocked drains. Service Corps is part-owned by Steve Cosser, a former Australian news presenter who started the country’s first pay television service.

Mr Mullins, who left school at 15 to take up a plumbing apprenticeship, founded Pimlico Plumbers in 1979 and has built it up into a business with a £15 million turnover and a reputation for promptness, reliability and eyewateringly steep hourly rates (£80 an hour, rising to £180 for a boiler engineer at weekend rates).

Such is his sense of outrage at Service Corps that he has engaged the services of the one profession even more expensive than a Saturday night plumber: the legal one. The solicitors Mishcon de Reya are on the case and counsel have been instructed.

Mr Mullins, 54, who paid himself £1.3 million last year — the company made profits of £2 million — says that since setting up in nearby offices in 2007 Service Corps has attempted to persuade his staff to breach their contracts, taken his company’s instruction manual — what he calls the “Pimlico Bible” — and obtained a confidential list of clients’ names and addresses.

Service Corps computers have been seized under a court order and examined for evidence to support Mr Mullins’s claims.

“It has been going on for about two years,” he said. “Then about six or eight months ago he tried to buy us out. I said: ‘There’s no way. It’s not for sale. It’s a family business. End of story’.

“It is not about the money. I could put the money down the drain. It wouldn’t bother me. But it’s not good for the industry. You need to send out a message that people need to conduct themselves properly.”

He added: “I take very seriously any attempt to take from me the fruits of more than 30 years of sweat and hard work.

“I have taken this to the High Court because I consider the actions of Service Corps and its directors to be underhanded and illegal in the extreme, and I will not stand idly by and let someone attempt to take away my livelihood, that of my family and all of my employees.

“I feel extremely strongly about this and I will not let the matter drop until due compensation is made to the company by those I feel are responsible.”

Mr Mullins said that if he wins, he will donate a lump sum to the charities he worked with when he appeared on the Channel 4 series The Secret Millionaire.

Mr Cosser, who has lived in both Australia and Britain, is a former chief executive of the TV network Channel 10. Two years ago he resigned from the Australian broadband provider Unwired, which he co-founded ten years earlier. Yesterday he declined to comment.

Explore Law

• Columnists

• Law Panel

• Law Reports

• Student Law

Times Recommends

• BGC 'set aside £40m to lure Tullett brokers'
• Legal aid review to ensure value
• Fears as 21 magistrates' courts face closure