The plan was for a morning of low-key door knocking for the Scottish Labour leader, Anas Sarwar, and Michael Shanks, the party’s candidate for the anticipated byelection in Rutherglen and Hamilton West, the seat held by the former Scottish National party MP and Covid rule-breaker Margaret Ferrier. But as the media descended, looking for Sarwar’s reaction to the arrest of the former first minister Nicola Sturgeon in Police Scotland’s investigation into the finances of the party she previously led, it was clear that the significance of this seat in the political landscape had again been heightened: once more the SNP was in turmoil and Scottish Labour primed to seize the momentum. “Look at the last 48 hours in British politics,” Sarwar told reporters, pointing to the “clown show” of Boris Johnson and the “absolute meltdown” in Scotland under the SNP. “It’s a perfect example of why we need change right across this country, both in Scotland but across the UK.” Last Friday, South Lanarkshire council confirmed the public petition to recall Ferrier would be open from 9am on 20 June, with constituents able to sign the document at seven different local amenities including leisure centres and Rutherglen town hall. The petition was triggered after MPs voted to suspend Ferrier – who was elected for the SNP but had been sitting as an independent – from parliament for 30 days following a recommendation of the Commons standards committee. If the petition is signed by more than 10% of eligible voters in the constituency within six weeks, Ferrier will be removed from her seat and a byelection called. This contest was already seen as a test of an apparent sea change in Scottish politics, with strong indications from recent polling that voters are now less likely to choose which party to back based on their constitutional preferences, as well as drifting support for the SNP following Sturgeon’s resignation, the bruising leadership campaign to replace her, and the stark questions about transparency and governance raised by the police investigation. Labour has been pouring resources into the constituency, with visits from Keir Starmer and other senior figures from the UK shadow cabinet, while local activists have been handing out glossy leaflets – labelling Ferrier “a criminal SNP MP who put lives at risk” – carrying a QR code for voters to add themselves to Labour’s email alerts once the recall petition goes live. Activists who knock doors regularly in the constituency report a tangible shift in reception on the doorstep since the start of the year, with people who voted the SNP into power 16 years ago now giving them a hearing. But this byelection is also a test for the new SNP leader, Humza Yousaf, after a gruelling start. While most SNP politicians and activists had anticipated their former leader would be spoken to by detectives in some capacity, the reality of her arrest was still a shock and left many frustrated and even despairing that – despite Yousaf’s best efforts to get on with the day job of government – the focus was again on the police inquiry. Following reports of Yousaf’s discontent with the calibre of potential candidates, the SNP selected a local councillor, Katy Loudon, for the seat on Friday. Party activists are well aware of the difficulties they face, but argue the time it has taken for Ferrier to be subject to a recall petition means voters have already made a distinction between her behaviour and the party she used to represent. The “clown show” Sarwar referred to brings his party another challenge in Rutherglen – with three other byelections required across the UK, will Labour resources and focus be split? On Monday morning, Sarwar would do no more than accept that the timing of the other byelections would be “interesting”. “I’m confident that we can get the necessary signatures required for that recall petition,” he said. “We then go the other side of summer recess and it’s on the SNP to move the writ and set the date for that byelection. We would obviously urge them not to delay in that process.” Shanks and his team will keep knocking on doors. “We’re confident of getting a good result,” said Sarwar, “but we’ve got to do the hard work. There’s no shortcut to that.”