When parliament returns in the autumn, it will have three new MPs, each of whom represents something unique about their party’s best chances of success at the next election. For Labour, Keir Mather’s victory in Selby and Ainsty was evidence of the power of the “change” message it hopes to sell to voters next year. At 25 years old, Mather will become the “baby of the house”, having run on the campaign slogan of “a fresh start”. After his victory on Thursday night, he told reporters: “As a young person in politics, I really hope to be a representative for the power that young people have to make a difference.” Labour officials will also take heart that Mather won by cleaving firmly to the main campaign messages of the national party, to such an extent it earned derision from his opponents. Johnny Mercer, the Conservative MP and minister of state for veterans’ affairs, told Sky News on Thursday night: “I think it’s always good to get new people in politics, but I think we mustn’t become a repeat of The Inbetweeners. “You’ve got to have people who have actually done stuff. This guy has been at Oxford University more than he’s been in a job. You put a chip in him there and he just relays Labour lines, and the problem is people have kind of had enough of that.” However, Labour said Mather’s victory was proof that voters had not had enough of candidates like him. Wes Streeting, the shadow health secretary, told the Guardian: “There was no doubt in my mind that he was going to go on to great things. “No pressure, but every Keir that’s been elected to the House of Commons has become leader of the Labour party.” The current leader, Keir Starmer, speaking later in Selby to celebrate the win, called Mercer a “silly sod” for his comments and said he would “soon be history”. But Brian Tolson, a Labour activist in Selby, said even local campaigners were surprised when they first saw their fresh-faced candidate, thinking he looked even younger than his 25 years. “To be honest, we thought at first: ‘God, is he old enough to vote?’ But he obviously is. And it’s a fresh start, isn’t it? Young blood. I think it’s good.” He said Labour had reaped the rewards of choosing a local candidate. “Don’t parachute people into areas. Let them be from the local area. He’s pretty local, from Brough, not too far down the road, and that does sway voters.” The Liberal Democrats’ chances of victory in Somerton and Frome looked to have taken a knock early in the campaign after their candidate, Sarah Dyke, struggled to answer questions about her party’s national policies in an interview with the Guardian. But Dyke’s victory showed the party’s history of strong local campaigning in the south-west is beginning to yield results again after several years of poor outcomes after going into coalition with the Conservatives in 2010. As well as serving as a local councillor, Dyke comes from a Somerset farming family that can trace its roots back 250 years. She won plaudits on the campaign trail for her knowledge of farming issues, even if her party occasionally caused irritation with the number of leaflets it pushed through letterboxes. For the Conservatives, however, there is one main message from Steve Tuckwell’s unexpected victory in Uxbridge and Ruislip: do not campaign on a Conservative platform. Tuckwell is a longstanding Conservative councillor in the area but barely mentioned the party or the prime minister on his campaign material. Instead of referring to himself as the Tory candidate, he called himself the “anti-Ulez candidate”, referring to the Labour mayor Sadiq Khan’s plans to extend the ultra-low emission zone to outer London. Tuckwell’s one-issue campaign paid off and gave the Tories a blueprint for how they might cling on to more seats than expected at next year’s election. If the party can find other such local “wedge” issues next year, they might be able to buck the national trend. The problem will be finding the issues that work and the candidates who might best exploit them.