DAVID Mundell has been urged to refer himself to the Commons ethics watchdog over his links to the group at the heart of a row over so-called Tory ‘dark money’.

The SNP said the Scottish Secretary should explain why he didn’t declare thousands of pounds of support from the controversial Scottish Unionist Association Trust (SUAT) in his parliamentary register of interests.

The Herald revealed yesterday that the SUAT, which is being investigated by the Electoral Commission over its status as a political donor, helped bankroll a campaign manager for Mr Mundell at the last two general elections.

Mr Mundell reported his campaign manager costs as £3488 in 2015 and £2400 in 2017.

The Tories said Mr Mundell didn’t need to register the money at the Commons as the SUAT gave it to his local party, not to him, to fund a campaign manager.

However the Commons Code of Conduct says MPs must register donations over £1500 given to a local party and there is “a clear link between the donation and [the MP]; for example, if it was given... with a wish that it be allocated... to his or her fighting fund”.

Mr Mundell, the MP for Dumfriesshire, Clydesdale & Tweeddale, has never declared any financial support from the SUAT in his register of interests.

Nor did he refer to the SUAT’s financial support in his office candidate return in 2015.

The salary for Mr Mundell’s campaign manager in 2017 was split 50-50 by the SUAT and Scottish Borders Conservative & Unionist Association.

The cost in 2015 was split between the SUAT and Tory HQ in London, although the Borders Association accounts do not say if this was also a 50-50 split.

However invoices from Mr Mundell’s campaign refer to 141 days “@ 50%”, suggesting it was an equal split.

If half the bill in 2015 was indeed met by the SUAT, this would be £1744, above the £1500 threshold for declarations in the register of interests.

The SUAT, which has given the Tories £319,000 since 2001, does not publish accounts or detail the source of its income, leading to SNP claims it is a source of so-called ‘dark money’, or untraceable political funding.

It was only after SNP Westminster leader Ian Blackford asked Theresa May about the SUAT in the Commons last month that it finally published a list of its trustees.

The SUAT chair is Robert Miller-Bakewell, who was Borders Association chair and treasurer in 2014 and 2015, when the SUAT began funding Mr Mundell’s campaign manager.

SNP MSP George Adam said: “The dark money scandal goes from bad to worse.

“There are questions over whether David Mundell failed to properly declare the benefit he received. Was he trying to hide something? In the interests of complete transparency it’s high time Mr Mundell was open and honest about the source of these funds.

“The Secretary of State should refer himself to the Commissioner for Standards to investigate whether he breached strict parliamentary rules over declaring political donations.”

Mr Miller-Bakewell did not respond to requests for comment.

A spokesman for the Scottish Conservatives said: “There is no requirement to place this funding on the MPs Register of Interests. This funding was not given to Mr Mundell or to his fighting fund. It was given to the local association to help fund regional campaign managers over recent years.

"In compliance with the rules, it was therefore registered as a donation with the Electoral Commission. "Mr Mundell properly declared the value of the campaign manager in his election returns in 2015 and 2017.

"As an MP of 13 years standing, Mr Mundell has a track record of complete transparency and every donation he has received in compliance with both the spirit and letter of the rules."?