Keir Starmer, who has just secured the biggest election victory in the UK this century to become prime minister, is considered reserved by the British public. In marked contrast to his best-known recent predecessor, the joke-telling Boris Johnson, Starmer invests the task of being a political leader with considerable seriousness, reflecting a career in which he was previously a human rights lawyer and, for five years from 2008, Britain’s chief public prosecutor. Making his first speech as prime minister outside 10 Downing Street on Friday, Starmer said with characteristic understatement that he would be a leader for “stability and moderation” and pledged “change, national renewal and a return to the politics of public service”. Starmer became the MP for Holborn and St Pancras, just north of central London, in 2015 and leader of the left-leaning Labour party in 2020, a year after its worst election defeat for 85 years. Now he has a 170-strong majority in the House of Commons. He will have to keep an eye on a potentially noisy group of five Reform UK MPs led by Nigel Farage, who will seek to focus on immigration and particularly people crossing the Channel in small boats. The last prime minister, Rishi Sunak, promised to stop the boats without having any means of doing so. There is no easy practical solution. That Starmer has brought the party of Tony Blair back into power so decisively after 14 years out of office is a huge achievement, but negative personal ratings from pollsters such as YouGov reinforce the idea that Starmer’s victory is a reflection of Conservative unpopularity. During the election campaign Starmer more successfully highlighted his relatively humble upbringing than his political agenda. In television appearances and news interviews he would repeatedly refer to his working-class background to counteract the idea he was an elite leftwing London lawyer. So many times had Starmer mentioned that his father was a toolmaker who worked in a factory that on one TV appearance the audience laughed at him when he said it again. In response, Starmer continued with his point, though slightly humourlessly. “It’s true – my mum was a nurse – and we couldn’t make ends meet. Which is not a laughing matter,” he said, emphasising the contrast with Sunak, whose family is worth over £600m largely through the wealth of his wife, Akshata Murty. Starmer fought a cautious campaign and he rarely misspeaks or provides his opponents with gifts to attack. His most serious misjudgment, particularly surprising given his past work in human rights, came last October, four days after Hamas’s deadly attack on Israel, when he was asked if Jerusalem had the right to besiege Gaza by cutting off power and water to the strip. “I think Israel does have that right,” Starmer replied, though he also emphasised the importance of respecting international law. Starvation, including denial of water and electricity, is generally considered a war crime, but it was nine days before he clarified that he had only meant to say Israel had a “right to self-defence”. Since then, Starmer has become quietly more engaged on the Gaza issue, with his party pressing for a tougher stance on Israel. He met Sheikh Tamim bin Hamad al-Thani, the emir of Qatar, a key mediator in the conflict, in early December and has discussed the Middle East crisis with Jake Sullivan, the US national security adviser. Critics on the left accuse Starmer of having dropped more radical policies that were a feature of his campaign to become party leader in 2020, which began with a slick campaign video that even emphasised his belief that the Blair-supported invasion of Iraq in 2003 was unlawful.