The Scottish Conservatives are increasingly confident of an historic victory in the Aberdeen South byelection after a tactical surge in their favour.

Party sources believe they have come from third place to overturn an SNP majority of almost 4,000 by a large margin.

If correct, it would be the first Conservative gain in a Westminster byelection in Scotland since Glasgow Pollok in 1967.

A formal declaration is expected around 2am.

Early indications suggest support for Labour and Reform UK - who came second and fourth at the 2024 general election - has collapsed.

An SNP source said the party had been on the receiving end of a 'tactical vote' against it, with the future of the oil and gas industry in the North East a key factor.

A Green source said the Tories had thrashed the SNP in the seat's affluent suburbs which are home to many workers whose jobs rely on North Sea drilling.

A clear SNP loss would be a humiliation for John Swinney in his first electoral test since the Peter Murrell scandal exploded in shocking detail.

Bruised after losing most of their MSPs at last month's Holyrood election, the Tories threw everything at Aberdeen South in a first step at recovery.

The party tried to turn the race into a local referendum on the oil and gas industry, claiming only they could be trusted with the future of the North Sea.

UK leader Kemi Badenoch was a repeat visitor, warning it was 'madness' to rule out new drilling in UK waters while relying on costly and more polluting imports instead.

As well as the focus on oil and gas, the byelection was fought against a backdrop of scandal.

During the campaign, ex-SNP chief executive Murrell pleaded guilty to embezzling more than £400,000 from party funds between 2010 and 2012 while married to Nicola Sturgeon.

For most of the period, Ms Sturgeon was also First Minister.

Murrell bought hundreds of luxury items using money from the SNP's main bank account, including Montblanc pens, designer watches, cars and a £124,000 camper van.

Despite a stream of deliveries to the couple's marital home near Glasgow, Ms Sturgeon has denied knowing or suspecting any wrongdoing by her now estranged husband.

Mr Swinney has refused to hold an inquiry into how Murrell was able to steal for so long, claiming the long-running police investigation that led to his conviction is enough.

The byelection was triggered by former SNP Westminster leader Stephen Flynn switching to Holyrood at last month's election, forcing him to give up his Commons seat.

At the 2024 general election, he held the seat with a majority of 3,758 over Labour, with the Tories 155 votes behind.

Mr Flynn won his Holyrood seat of Aberdeen Deeside thanks to Reform UK splitting the anti-Nationalist vote - their 6,113 votes dwarfing the SNP lead of just 1,244.

The Conservatives used their painful defeat in Aberdeen Deeside to warn voters against making the same mistake in Aberdeen South and ending up with 'buyer's remorse'.