More than a thousand people are planning to descend on Downing Street on Saturday in a demonstration against David Cameron’s links to offshore finances.
Organisers were urging protesters to don their most garish Hawaiian shirts and practice “calypso moves” for the rally, which comes amid calls for the Prime Minister to resign.
A huge leak of documents from a law firm in Panama revealed that his father had run an offshore fund called Blairmore Holdings, which was not set up to avoid tax.
Downing Street originally declined to respond to questions on the “private matter” or Mr Cameron’s finances but he subsequently admitted to owning a stake in the fund, which he sold for £31,500 before he took office in 2010.
There is no suggestion of any wrongdoing but critics accused Mr Cameron of hypocrisy, saying he should have been more transparent even without the Panama Papers.
The organisers of Saturday’s protest, entitled "David Cameron: close tax loopholes or resign", said the leak showed the Prime Minister had been “taking the general public for fools”.
“Because so many UK companies are based in Panama, the British Virgin Islands and other tropical tax haven hotspots we want to make them feel at home - so let’s dress for the occasion!” the Facebook page said.
“Hawaiian shirts, tropical colours, sunglasses and (of course) Panama hats. If you've got a blow up beach ball then bring that along.
“Why should Tories get to have all the offshore fun?”
Opposition politicians are pushing for Mr Cameron to answer questions on the matter in the House of Commons on Monday.
He was one of several current and former leaders, including the Prime Minister of Iceland, linked to offshore accounts by files from Panama law firm Mossack Fonseca.
Mr Cameron said it was a “fundamental misconception” that Blairmore was set up to avoid paying UK tax and stressed that his interest in it had been “subject to all the UK taxes in the normal ways”.
He paid income tax on dividends but the £19,000 profit on the sale was insufficient to attract capital gains tax.
“I want to be as clear as I can about the past, about the present, about the future, because, frankly, I don't have anything to hide,” Mr Cameron told ITV News.
Additional reporting by PA
