Labour won a by-election in Fortissat, North Lanarkshire, from the Conservatives, with the Scottish National Party in third place on first preference votes. Progressive unionists celebrated. But attention has also turned to the party that came second, the Unionist Party.

Despite its name, the party is so obscure that former Better Together heavyweights were Googling it this morning.

“A Better Britain Unionist Party” – not to be confused with the Scottish Unionist Party, which has been going since 1986 – was formed in late 2015. According to the party’s website, it was founded by grassroots unionist activist who were involved in the Better Together campaign.

It opposes further devolution, referendums, and backs Brexit. Despite being in submarine mode, the party has stood candidates in the 2017 council elections and the 2016 Scottish parliamentary elections.

“Unionist Party humiliates SNP,” it declared after Thursday’s by-election result. The mainstream pro-union movement, though, is not joining in the celebrations.

In Scotland, there have long been attempts to distance the pro-union argument from the unionist politics that overlap with Protestant identity, the Orange Order and British nationalism. Despite Ruth Davidson’s elevation to national stardom, at the grassroots level the Scottish Tories are trying to recover from a scandal in which two Stirling councillors were found to have posted anti-Catholic and racist abuse before their election in May.

The vote for the Unionist Party is believed to come from a distinctly Protestant voter bloc, which until now has backed the Scottish Tories or Scottish Labour. In May, shortly after the council elections, Jim McHarg, the grand master of the Grand Orange Lodge of Scotland, a controversial Protestant organisation, said at least six members had been voted in as councillors, for both the Conservatives and Labour, including in Lanarkshire.

One source close to the mainstream pro-union movement described the Unionist Party as a fringe group, but added: “There has been a reawakening of Orange identity.”

But while the Unionist Party may put anti-sectarianism campaigners on edge, for now, it is unlikely to pose a serious threat to the mainstream pro-union parties. The biggest problem, instead, may be containing the excesses of grassroots unionism within their own ranks.