Former British prime minister David Cameron said Friday he had no regrets about launching the Brexit referendum but accused current PM Boris Johnson of behaving “appallingly” during the pre-vote campaigning.

Cameron, 52, who led the failed Remain campaign for Britain to stay in the European Union, told The Times newspaper that the tortuous Brexit negotiations were “painful to watch”—and losing office left him “hugely depressed”.

Prime minister for six years, Cameron has largely kept his counsel since he left office following the 2016 Brexit referendum.

His long-awaited memoir, “For The Record”, is due out on Thursday.

Cameron said current Prime Minister Boris Johnson—an old schoolfriend—behaved “appallingly” during as head of the successful Leave campaign ahead of the referendum.

The former premier said a no-deal Brexit would be a bad outcome and that he would have backed the withdrawal agreement rejected by MPs.

Britain is due to leave the EU on October 31.

Cameron told The Times that a referendum on Britain’s relationship with the EU had long been promised by politicians and the bitter divisions between Leavers and Remainers now gripping Britain were there long before the seismic vote.

“The country was divided whether we should be in the EU before the referendum,” Cameron said.

“This issue needed to be addressed and I thought a referendum was coming, so better to try to get some reforms we needed and have a referendum.

“But I accept that, you know, that effort failed. I do understand some people are very angry because they didn’t want to leave the EU. Neither did I.”