Sam Gyimah has become the latest MP to defect to the Liberal Democrats, becoming the 18th Liberal Democrat MP and the third MP elected under Conservative colours in 2017 to join the party, in a major boost to the party and its leader, Jo Swinson, at the close of the party’s first full day.

The defection of Gyimah, who served as David Cameron’s parliamentary private secretary and was tipped to hold high office, is a particular coup as the party eyes a target seat list that is rich in Conservative-held seats. The party’s successes so far have been underpinned primarily through the capture of Labour votes. The party’s strategists still believe they can get more votes out of the Labour party, which is part of why they have unveiled their latest defector in the Observer, but they also know that if they want to crack 25 per cent, they need to win over more Conservative Remainers.

Gyimah’s comments in his speech that “something has gone wrong” in the state of the Conservative party is partly about Brexit – but what the Liberal Democrats want is for that critique to be the foot in the door, to force a larger shift among Conservative voters.

But they also have a job to do reassuring the significant minority in their activist base that the party isn’t sacrificing its soul in order to achieve that aim. That’s part of why Swinson made sure to emphasise Gyimah’s support of same-sex marriage and their long friendship in her introduction, and why Gyimah’s introduction focussed on his political journey. It was also why he took care to say publicly what close allies of Swinson have insisted privately for some time: that despite the rumours that she would facilitate electoral pacts to help independent Conservatives she is, as Gyimah quoted her as saying, “in the business of creating Liberal Democrat MPs, not bailing out Conservative MPs” when he first mooted that he would run as an independent with Liberal Democrat support.

This is another defector that happened in large part because of Swinson’s close personal connections, a central plank of her leadership bid. On that measure, her tenure is already a success. But her next test – to add Liberal Democrat MPs via election and not defection – is bigger still.