SCOTTISH Secretary David Mundell directly benefitted from the group at the heart of row over so-called Tory ‘dark money’, electoral records have revealed.

The secretive Scottish Unionist Association Trust (SUAT) helped pay the salary of Mr Mundell’s campaign managers at the last two general elections.

Mr Mundell’s campaign manager costs were £3,488 in 2015 and £2,400 in 2017, however his official candidate return did not mention the SUAT partly bankrolled the posts.

The SUAT, which has given the Tories £319,000 since 2001 but does not publish accounts, is currently under investigation by the Electoral Commission over its status as a donor.

It was only last month, after the SNP challenged Theresa May over the SUAT at Prime Minister’s Questions, that the shadowy outfit first named its trustees.

The SNP last demanded full transparency from the Scottish Secretary on the issue.

The money trail from the SUAT to Mr Mundell emerged yesterday when the Electoral Commission published the accounts of hundreds of small party branches across the UK.

These included the Scottish Borders Conservative & Unionist Association (SBCUA), which covers the Tweeddale part of Mr Mundell’s Dumfriesshire, Clydesdale & Tweeddale seat.

The accounts for 2017 said the SBCUA had a paid campaign manager overseeing a series of elections, including Mr Mundell’s general election fight.

“The Association is very grateful to the Scottish Unionist Association Trust for providing 50% of the funds for this crucial campaigning position throughout 2017, with the Association itself being responsible for the balance,” it said.

However there is no public record of the SUAT donating directly to the SBCUA in 2017.

Other SBCUA accounts showed the SUAT also part-funded a campaign manager for Mr Mundell in 2014 and 2015 in the long build-up to the 2015 election.

The cost split was not given, but official election invoices listed the campaign manager costs as “103 days @ 50%” and “38 days @ 50%”.

The SUAT gave the SBCUA at least £12,336 in 2014 and £6,168 in 2015.

The SUAT and SBCUA also jointly funded a campaign manager for Tory MP John Lamont in Berwickshire, Roxburgh & Selkirk in 2015 and 2017.

During the 2015 election, the chair and treasurer of the SBCUA was former Merrill Lynch consultant Robert Miller-Bakewell, the chair of the SUAT.

He was also deputy chair and deputy treasurer of the SBCUA at the 2017 election.

Mr Mundell has denied getting cash from the SUAT, but has not denied campaign help.

However he was cagey about the issue when quizzed on BBC Radio Scotland last month.

He said: “I personally have not received cash because we go through a process of funding associations and I am confident that over the full period during which I have been involved in politics, all donations I have received from any source have been appropriately declared.”

Asked him much money his campaign had received, he said: “That is a question that can be sourced from all the declarations.”

SNP MSP George Adam said: “The Tory dark money scandal is a running embarrassment for the party, and they're doing themselves no favours in trying to hide from scrutiny.

"David Mundell has repeatedly tried to deny his links to the Scottish Unionist Association Trust. Now it seems they helped bankroll his election campaign.

“We're talking about one of the most senior Tories in Scotland here. He should be open and honest over where this money came from.

“Transparency over party finances is absolutely essential in any healthy democracy. The public have the right to know who helped put their politicians into office."

The Electoral Commission yesterday said it would not be investigating a ‘dark money’ row involving the DUP, a former Scottish Tory, and the EU referendum.

A BBC Northern Ireland TV programme alleged the DUP may have worked improperly alongside other pro-Brexit campaigners.

The DUP accepted £435,000 from the Constitutional Research Council, chaired by former Scots Tory candidate Richard Cook, on the eve of the referendum, which was then spent on newspaper ads in the UK.

The Commission said it did not have grounds to open an investigation into the allegations.

However it also urged the UK government to bring forward legislation allowing it to disclose details of past donations to Northern Ireland parties, which are currently kept secret.

Mr Mundell is currently on a UK Government trip to New Zealand.

The Scottish Conservatives said all SUAT donations to the party and all election spending had been properly and fully reported to the Electoral Commission in line with the law.

A spokesman said: “The money donated from the SUAT comes from the proceeds of the sale of Scottish Conservative properties in Scotland in the 1960s.

“Since then, the SUAT has used those funds to promote the interests of the party.

"These publicly registered documents show that the SUAT has helped fund a campaign manager for the SBCUA in recent years, as it has supported other Associations across Scotland. In 2017, this amounted to 50 per cent of the cost of the campaign manager."