"I think the 50p tax rate has encouraged people to be even greedier than they were," said one Scottish tax adviser this week after it emerged that tax avoidance schemes were enabling celebrities to pay as little as 1% tax on their income.

But after comedian Jimmy Carr found paparazzi camped outside his house with his reputation under heavy fire, high earners using tax boutiques for magic bullets might be feeling a little nervous.

In September 2010, Treasury Secretary Danny Alexander promised a £7 billion crackdown on tax avoidance and warned: "To those who hire accountants to dream up a clever new tax dodge, I say think again."

But as The Herald revealed at that time, schemes can be sold as legal and run for years before being challenged by the taxman, delivering significant tax savings for a client and juicy fees for the advisers.

Premier Strategies, an arm of mid-tier accountant RSM Tenon, had told its clients: "All of our strategies have been exhaustively researched and all have received counsel's opinions from a number of leading QCs and barristers."

But as with other firms, that did not mean a scheme had been cleared by the Revenue and the client had no comeback in the event of it being declared illegal years later.

Last month, RSM Tenon told the Stock Exchange: "Following the announcement of a general anti-avoidance rule in the recent UK Government budget, we have decided not to offer further new products through our specialist tax service line."

The Government has promised a general anti-abuse rule next March following a consultation by Graham Aaronson, QC, who said this week he paid 50% tax and was "absolutely furious when people tell me they pay 3% because of some scheme".

Aidan McLaughlin, partner at advisers McLaughlin Crolla in Glasgow, said: "It is actually a good consultation. Mr Aaronson has been all around the world and discovered that the last thing you want to do is have the Revenue draughtsmen come up with new legislation."

The QC wants the Government to enshrine in a new law the principle of "abnormal transactions", which would outlaw 95% of artificial planning, but would mean "the Revenue won't catch genuine transactions just because they don't like them," said Mr McLaughlin.

He said that since the "big four" accountancy firms had been required by the Government more than a decade ago to notify the Revenue of any scheme it created, the market had been colonised by tax boutiques. "Many don't have any qualms about putting schemes in front of clients because their clients are gamblers," he said.

"As long as they know the downside, they are prepared to take a chance."

But Mr McLaughlin said recent high-profile challenges by the Revenue to dodges such as the Eclipse film investment scheme, patronised by the likes of Wayne Rooney and Frankie Dettori, had sent out a warning.

"When they can ride a coach and horses through these sorts of arrangements, on which huge care and probably millions of pounds have been spent, they are just going to make hay with the likes of K2."

Peak Performance, the Kirkcaldy-based consultant, which runs the K2 scheme used by Mr Carr and more than 1000 others to shelter £168 million of tax, is careful to warn on its website that clients "should be aware of the downside".

The Revenue has already signalled that it will move against such schemes, which transfer salaries into offshore trusts and repay the cash as "loans".

Mr Carr, meanwhile, can also be caught at the Edinburgh Festival Fringe, where the programme urges with unintended irony: "Leave your conscience at home and come on out for a laugh."