British prime minister Theresa May repeatedly failed to back her predecessor David Cameron in his fight to keep Britain in the European Union and hampered his attempts to rein in migration, according to extracts from two books about the referendum.
Ms May, who served as home secretary under Mr Cameron and succeeded him as prime minister when he resigned after Britain’s vote to leave the EU, backed staying in the bloc but was largely absent from the campaign.
The two books come as Ms May faces the complex task of leading negotiations over Britain’s EU divorce, having divulged little on her intended strategy.
Extracts from a book by Sunday Times political editor Tim Shipman said that Ms May refused to support Mr Cameron in seeking to take a harder line on immigration in his deal with Brussels to reform Britain's relationship with the EU.
Ms May told Mr Cameron that he should not press ahead with demands for an "emergency brake" to limit the number of EU migrants coming to Britain because Germany would not back it, the newspaper reported.
A separate book written by Mr Cameron's former head of communications Craig Oliver details more than 10 occasions when Ms May declined to back Mr Cameron during the referendum campaign.
Mr Cameron’s team dubbed her “Submarine May” for disappearing when she was needed, Mr Oliver said.
“Her sphinx-like approach is becoming difficult, with the press questioning which way she will jump,” Mr Oliver wrote in the book, extracts of which were published in the Mail on Sunday newspaper.
Mr Oliver said that Mr Cameron had asked Ms May to back his plan to crack down on migrants coming to Britain to claim social security payments but she issued a statement describing it simply as “the basis for a deal”.
Conservative Party chairman Sir Patrick McLoughlin sought to play down the claims, insisting that Ms May had been “very much part” of the Remain campaign. Asked on Sky News’s Murnaghan programme if Ms May had “let down” Mr Cameron, he said: “I don’t think that is true at all. Theresa May during the referendum campaign made her position very clear.
“This is a book that has been written after the event. You have got to have certain spicy things in a book to sell it. I don’t blame Craig for doing that. At the time, Theresa was very much part of the Remain campaign.”
However, former Northern Ireland secretary Theresa Villiers, who campaigned for Leave, said she believed Ms May had been listening to both sides. "There were times that I did wonder," she told BBC One's Sunday Politics programme.
"Her major speech of the referendum campaign expressed real concerns about the possibility of Turkey joining the EU. It also said that the sky is not going to fall in if we leave. I think she was genuinely listening to both sides."
Mr Oliver also said that Boris Johnson – a leading Brexit campaigner and now foreign minister – "wobbled" over backing a Brexit and told Mr Cameron that he would be supporting the Leave campaign only nine minutes before announcing it to the media.
In his text message to Mr Cameron, Mr Johnson made clear he did not expect to win, saying Brexit would be “crushed”, Mr Oliver said.