Angry Leave voters will spoil their ballot papers by writing 'Brexit Party' on them in seats where Nigel Farage has stood down his candidate, according to the lawyer who mediated failed electoral talks between Mr Farage and Boris Johnson.

Andrew Reid, a London-based solicitor, mediated the talks because of his position knowing both Mr Farage and Mr Johnson - he has lent office space to both men in the past and was Ukip's treasurer when Mr Farage was leader.

The Telegraph disclosed today that the Conservatives offered an electoral pact to Mr Farage that would mean the Brexit Party targeting just 40 key seats and soft pedalling in the rest.

Mr Johnson was prepared to put up “paper candidates” in the Labour-held constituencies, meaning the Tories would carry out only minimal campaigning in order to give an advantage to Brexit Party rivals.

However, the deal was turned down by Mr Farage, who insisted on the Tories withdrawing their candidates altogether from the seats, because he was worried that the Conservative candidates would still attract votes.

The Conservatives have insisted there had never been any formal talks with the Brexit Party, but multiple sources have told The Telegraph there were twin-track talks behind the scenes.