Are the Liberal Democrats about to welcome their second defector in as many months? Heidi Allen, the former Change UK leader, has joined the party on the campaign trail ahead of next week’s by-election in Brecon and Radnorshire.

The former Tory MP for South Cambridgeshire now sits in the Commons with the Independents, the self-described political co-operative founded by those who quit Change after its abysmal showing in May’s European elections. Allen’s preference for cross-party cooperation with the Liberal Democrats was one of the issues that precipitated Change’s split, and she has never ruled out following Chuka Umunna in defecting.

Lib Dem sources told the NS that, while Allen had not yet defected, she had offered to travel to Wales to campaign for Jane Dodds, their by-election candidate, of her own accord. “She hasn’t joined us yet,” said one official, “but she is spending the day in Brecon to help elect a Liberal Democrat. She offered to come to help, all in aid of beating the Tories."

The party is increasingly confident of overturning a Conservative majority of 8,038 when voters in the Welsh constituency, which it held until 2015, go to the polls next week. Dodds’ predecessor as Lib Dem leader in Wales, Kirsty Williams, hold the coterminous Welsh Assembly seat. Though the race has been written up as a straight fight between the Lib Dems and the Brexit Party, Nigel Farage has not yet visited the constituency and his outfit’s campaign infrastructure is decidedly threadbare.

Jo Swinson, by contrast, has visited the seat four times. Should Dodds succeed in unseating Tory Christopher Davies - who is running again despite being recalled by constituents after his conviction for expenses fraud - she will reduce Boris Johnson’s working majority in the Commons to just one.