Tim Martin, chairman and founder of the pub group JD Wetherspoon, has seen £18 million wiped off the value of his shares in the days following the Brexit vote - a very poor return on the £224,000 he spent on campaigning to leave the EU.

Martin has been an outspoken critic of David Cameron and the Remain campaign, calling the prime minister's language divisive, "sectarian" and reminiscent of the rhetoric of the late Ian Paisley, the former leader of Northern Ireland’s Democratic Unionist party.

The multi-millionaire campaigned for Brexit through his network of 920 pubs, touring up to 100 outlets in the weeks before the crucial vote to persuade punters to opt for Brexit and even distributing 500,000 beer mats calling for the UK to leave the bloc.

The mats, which bore Martin’s signature, and were addressed to George Osborne, asked, “Does the nation not deserve more independent advice?”

They drew attention to the Chancellor’s friendship with Christine Lagarde, the managing director of the IMF, a body which he compared to corruption-ravaged football governing body, FIFA.

He also questioned the Chancellor’s connections to Jose Angel Gurria, current secretary-general of the OECD, which said that Brexit would be bad “from every single angle”.

Beer mats urging customers to vote to leave the EU (JD Wetherspoon)

Indeed, Brexit has, at least in the short term, turned out badly for Martin personally, who saw Wetherspoons' share price crash from a high of £7.57 on the day of the vote to £6.68 four days later, leaving him £30 million worse off.

The shares have since regained some of their value as markets have stabilised but his paper losses still stand at around £18m.

The amount is small beer to the entrepreneur though. His 30 per cent stake is worth around £260 million.

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Speaking to The Independent, Martin said that any losses were short term and unrelated to the referendum. "No sensible analyst could attribute the price drop to this one event specifically. Look at the FTSE, it's higher than it was before the vote."

He pointed out that Wetherspoons' share price is within the range it has been for the last year and urged people to look at the company's fundamentals.

"If you try and judge fluctuations in prices day-to-day all that will happen is you'll go completely mad and need a heavy dose of valium," he said.

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Martin insists prospects for Wetherspoons and the UK economy have improved since the decision to leave the EU.

"A higher level of democracy always leads to higher economic growth. Look at North Korea versus South Korea, West Germany versus East Germany. The EU is not democratic."

Martin was not the only Brexit donor to suffer financial losses after the vote. Hargreaves Lansdown owner, Peter Hargreaves gave £3.2m to the Leave campaign then saw £300m wiped off the value of his firm.