Theresa May has joined the Conservative heavyweight pile-on against Rishi Sunak over HS2 as she becomes the third former Tory prime minister to call for the project not to be axed . Asked on Saturday if she would cut HS2, the former Tory leader responded with a categoric ‘no’ over fears that abandoning the line into Euston will disrupt trains from her constituency, Maidenhead in Oxfordshire. She also warned that scaling back the project would leave the North West without the railway capacity it desperately needs. Her intervention came as the prime minister prepares to take the stage at the Conservative Party conference next week following The Independent ‘s revelations that he is secretly planning to cut the high-speed rail project – prompting a barrage of criticism from Tory grandees , businesses and regional mayors . Boris Johnson , who succeeded Ms May, warned on Friday that Mr Sunak and Mr Hunt would be ‘out of their minds’ to abandon the flagship transport levelling-up project, while her predecessor David Cameron is said to have privately raised concerns with Downing Street. In a wide-ranging interview with The Independent ‘s Simon Walters at the Henley Literary Festival , of which The Independent is the exclusive news partner, Ms May also admitted errors from her time in office, but insisted that her Brexit deal had been the best choice for the UK. She also reflected on being perceived as a ‘typical weak woman’ after she welled up during her speech when she resigned as PM in 2019. Asked during the Q&A whether HS2 should be abandoned, Ms May said: ‘The answer is no. I will give you two comments on HS2. ‘First of all, we have to think about why HS2 was designed in the first place. It was because there was a lack of capacity on the West Coast Main Line. So if there is a lack of capacity on the West Coast Main Line, we need more railway capacity to serve the North West.’ Theresa May has joined fellow former Conservative Prime Ministers in piling the pressure on Rishi Sunak with calls to not scrap HS2 She said there was also an issue for her constituents if the line does not end up terminating in Euston, in central London. ‘If HS2 stops at Old Oak Common, it is going to make our railway journeys into London longer and disrupted potentially over the period that Old Oak Common’s building is being done to enable it to take that endpoint. ‘So I am arguing with Government: ‘Don’t stop at Old Oak Common. You need to take it into Euston because my constituents will be disadvantaged if you don’t’.’ Speaking at the festival on the release of her new book, The Abuse of Power, Ms May took a swipe at both Mr Sunak’s and Mr Johnson’s Brexit deals , arguing that her proposed deal was ‘better than the one we finally got’. She slammed Mr Johnson for accepting the Northern Ireland Protocol, creating more checks at its border with Ireland. She said that at the time she thought: ‘No UK PM could accept that as it would put a border down the Irish Sea between Ireland and Northern Ireland… but Boris accepted it.’ And while she conceded Mr Sunak’s deal was an improvement, she said checks still remain. ‘He’s found a way through,’ she said. ‘I have every expectation that it will work. But it’s slightly different to a deal that I would’ve done.’ Ms May also admitted to many of her own failures while at Downing Street, saying that, before writing her book, ‘I thought it was important to look myself in the mirror.’ Ms May announced her resignation in May 2019 Asked about ‘big mistakes’ she acknowledges – such as her social care reforms proposal that was branded a ‘dementia tax’, or her decision to call a snap General Election in 2017 that lost the Conservative Party their majority -she said: ‘You need to reflect on what you might have done wrong. If you don’t then you can’t learn for the future.’ On getting emotional during her resignation speech, she added: ‘One of the issues for women in politics is that if you show any emotion, it’s seen as being a typical weak woman. But if a man in politics does so, it’s seen as ‘isn’t it good he’s showing his other side’.’ Ms May also accused those in power of ‘serving themselves rather than those who are powerless who they should be serving’.