A former Scottish Tory candidate embroiled in the row over a £435,000 “dark money” donation in the Brexit referendum could be summoned to give evidence to a Westminster committee.

SNP MP Brendan O’Hara said it was “imperative” that Richard Cook, chair of the secretive Constitutional Research Council, answered questions in front of MPs about the CRC’s infamous donation.

He believes Cook should be quizzed by members of the Digital, Culture, Media and Sport (DCMS) committee, which has focused on the leave campaign as part of a wider probe.

It emerged last year that the CRC had ploughed in around £435,000 to the pro-Brexit Democratic Unionist Party (DUP) in Northern Ireland during the referendum campaign.

However, although the cash was given to a party in Ulster, much of the donation was spent on the mainland in the form of a wraparound advert in the Metro newspaper, which is not sold in Northern Ireland.

Despite the size of the donation, the DUP was under no obligation to name the CRC as the source – declaration laws did not apply then to Northern Ireland – and did so voluntarily.

CATCH UP: What happened when the Sunday Herald spoke to Cook

The only detail to come out about the CRC is that Cook, who failed on several occasions to get elected for the Scottish Tories, chairs the body.

He confirmed the CRC has an executive committee, but has declined to name its members, put a figure on how much it has raised, or talk about other specific causes that have been funded.

Cook, who owns a modest house in East Renfrewshire, has also consistently refused to say who gave the CRC the £435,000. He is under no legal obligation to provide the donor names, prompting critics to describe it as an example of “dark money”.

The Herald:

Image: Cook (left) during the 2010 general election campaign

The DCMS last year launched an inquiry into the growth of so-called “fake news” and the impact it has on the “public understanding of the world” and on traditional journalism.

The committee, which issued an interim report recently, focused heavily on some of the tactics used by pro-Brexit groups during the referendum.

MPs have been praised for the work carried out as part of the probe, but have been hampered by the refusal of senior Vote Leave figure Dominic Cummings to attend.

Given the CRC’s prominent role in the referendum, O’Hara has written to the committee's chair, Tory MP Damian Collins, and called for Cook to give evidence.

He told this newspaper: "I have called on the DCMS Committee to summon Mr Richard Cook to give evidence to our on-going inquiry into the vote leave campaign. It is imperative that we have a full understanding of his role, how the CRC processed £435,000 to the DUP and whether he booked the infamous Metro advertisement for Vote Leave."

He added: "It's time we had some answers – Richard Cook should help the DCMS Committee with their investigations and provide some much needed clarity."

Speaking to the Sunday Herald last year, Cook said of the body he chairs: “The CRC is regulated by the Electoral Commission. We operate solely in the UK. We accept donations only from eligible UK donors. We donate solely to permissible UK entities. Any suggestion that we have done anything else is basically defamatory.”

Explaining the CRC’s internal decision-making process, he said: “The process is quite simple: people come to us with projects [and] they tell us how it is promoting the Union. The Executive Committee assess that and will decide. I don’t decide on my own. I’m just part of the process.”

On who had contributed financially to the CRC, he said: “I’m not going to get into the donors, like I am not going to get into the members.”

Asked if any Scots had donated to the CRC, he replied: “Yes.”

Cook has made several attempts at getting elected for the Scottish Tories, such as when he polled 13.4% in Glasgow Cathcart in 2001. He came third again the same seat four years later in a Holyrood by-election.

In 2010, he tried to dislodge Labour’s Jim Murphy in East Renfrewshire, but lost by around 10,000 votes.

Cook did not provide a comment for the story.