A former Conservative minister has quit the party, claiming it is dominated by “ideology and self-obsession”, and has instead thrown her support behind Keir Starmer. Claire Perry O’Neill, who was part of Theresa May’s cabinet and was briefly retained by Boris Johnson to help run preparations for the Cop26 summit, praised the Labour leader’s “sober, fact-driven, competent political leadership”. Perry O’Neill, who was a Tory MP from 2010 to 2019, said she liked and admired the prime minister, Rishi Sunak, and the chancellor, Jeremy Hunt. But in an article, she said the pair had become too beholden to inter-party factions to “deliver the big changes we need in a fact-based, competent way”. “I spend most of my time now working in the private sector and this is not the way to build back confidence and deliver investment, especially in the crucial energy sector,” Perry O’Neill wrote in the Times. Since leaving the government, she has held senior advisory positions – including at the consultancy firm McKinsey & Co, as well as Scottish Power. Perry O’Neill said she had quit the Conservatives earlier this month. “My former party’s often cavalier approach to business and academia coupled with a post-Brexit reluctance to strategically engage with our European neighbours has damaged our ability to deliver the energy system we need,” she said. However, Perry O’Neill lavished praise on Starmer. She said Labour had put “energy at the top of their proposed new government inbox”, and applauded its ambitions for green technologies and a national low-carbon wealth fund. She added: “Even more important is their proposed focus on a new way of governing, focused on measurable outcomes not short-term shout-outs. “Building a low-carbon, secure, affordable energy system for the UK is an immense challenge that needs sober, fact-driven, competent political leadership. I sense that is exactly what we will get should Labour win the next general election.” The move risks undermining Sunak’s attempt to cast himself as the leader of a united party. Starmer addressed Labour MPs in a private meeting to kick off the party’s 2023 strategy on Monday night, saying the year would be spent “setting out the plan” for Labour in government. He said of the two speeches given last week – by Starmer and Sunak – there were “competing visions for Britain … the prime minister setting the bar so low for his promises to the country that he could hardly fail to flop over it”. Starmer insisted Labour was the party of hope, change and optimism – and had a “proper plan to make all that change happen”, referencing a pledge for further devolution, as well as policies on jobs, skills and the NHS workforce. He said the prize at the end was “massive” – a chance to “add ‘24 to ‘45 and ‘97 in the history books”.