Former Ukip leader Diane James signed official papers using the Latin term for “under duress” during her 18 days in office in a bizarre turn of events even for the standards of the Eurosceptic party.

Ms James stunned Ukip members by quitting on Tuesday night after less than three weeks in the job.

Within hours a furious row erupted after it emerged that Nigel Farage was still technically the leader of the party.

Problems with Ms James’s paperwork meant that she had never been formally registered in the position with the elections watchdog, the Electoral Commission.

The commission said that it had only received the forms on Monday and that they had yet to be processed because of outstanding questions.

Documents released hours later under the Freedom of Information (FOI) Act showed that Ms James signed her official registration form with the words Vi Coactus, the Latin phrase for under duress.

Earlier, the party’s migration spokesman Steven Woolfe had thrown his hat in the ring to replace her, despite a shock admission that he had considered defecting to the Conservatives as recently as last week.

Mr Woolfe was himself barred from standing during the last leadership contest because of a problem with his paperwork.

The then frontrunner submitted his nomination papers 17 minutes too late to join the race over the summer.

Mr Woolfe is seen as a skilled pair of hands who can appeal to disgruntled Labour voters in the north of England.

He said that if elected he would seek to supplant Labour as the main opposition party at Westminster.

But he admitted that Mrs May's start to her premiership has caused him to consider joining the Tories.

"Her support (for) new grammar schools, her words on social mobility and the growing evidence that she is committed to a clean Brexit prompted me, as it did many of my friends and colleagues, to wonder whether our future was within her new Conservative Party," he said.

However, he said, he concluded just last weekend that only Ukip could guarantee Brexit was delivered in full.

There was speculation that he will be challenged by Suzanne Evans, the party's former deputy chairman, who has been cleared to stand after her suspension from the party was lifted.

The party's leader in the Welsh Assembly, former Tory MP Neil Hamilton, is also tipped to run after he called on Mr Farage to stand aside as interim leader, saying that it would be a "mistake" to carry on.

David Coburn, Scotland's only Ukip MEP, ruled out standing saying that he would support Mr Woolfe.