David Cameron’s publisher has insisted that the former prime minister’s memoirs are still due out this autumn “as planned”, following reports that the autobiography has been delayed due to the extended Brexit deadline.

Cameron sold his memoir to publisher William Collins for a reported £800,000 in 2016, promising that he would “be frank about what worked and what didn’t”. The deal came shortly after he stepped down as an MP to avoid being a “distraction” to Theresa May.

In 2017, his purchase of a £25,000 “luxury” hut to use as a writing studio was widely reported; by January this year, his word count was reportedly topping 400,000, and he is said to have been asked by William Collins to cut 100,000 words from the volume. The autobiography was initially scheduled for 2018, but was delayed until autumn 2019, in order that Cameron avoid being seen as a backseat driver in the prime minister’s handling of Brexit.

But the Daily Mail’s Sebastian Shakespeare reported on Thursday that Cameron had now told him: “I honestly don’t know when it’s coming out.” According to Shakespeare, Cameron gave May an understanding that his memoirs would be delayed until after Britain left the EU to “not to rock the boat”. But with the new extension to 31 October granted on Wednesday, the Mail said that publication was “on hold with no date set”, despite plans for Cameron to begin publicising the memoirs in April.

William Collins, however, denied that the memoirs were on hold. “We are publishing this autumn as planned,” a spokesperson told the Guardian on Thursday.

The title of Cameron’s memoir has yet to be confirmed.