Who is Arron Banks?

Arron Banks came on to the political scene suddenly in 2014, when he agreed to donate £1m to Ukip. He had planned to give £100,000, but upped the amount after the former Conservative leader William Hague said he had not heard of him.

Colourful and outspoken, Banks quickly became a key figure in Ukip, close to the then party leader, Nigel Farage, and was part of the group who visited Donald Trump at Trump Tower shortly after his presidential election victory in November 2016.

Banks owns the insurance company GoSkippy and gave £9m to the Leave.EU and Grassroots Out Brexit campaigns, mostly in the form of loans and branded merchandise. His wife, Katya, was born in Russia. They have three children and have been married since 2001.

What is he alleged to have done?

Emails leaked to the Observer and the Sunday Times reveal Banks, Farage’s main financial backer in the run-up to the EU referendum, had far more extensive contacts with Russian officials than he previously claimed.

The emails show he met the Russian ambassador to the UK, Alexander Yakovenko, three times, rather than once, that Banks shared at least one phone number for the Trump transition team with the Russians, and that he was offered the chance to participate in a goldmining deal in Russia, although it is not clear whether he took this up.

Why are the leaks so serious?

There has been persistent speculation about Banks’s relationship with Russian officials in the UK since he disclosed that he and his colleague Andy Wigmore had a “six-hour boozy lunch” with the Russian ambassador on 6 November 2015. But Banks has now been forced to admit the contacts were deeper than previously stated.

They also met the ambassador on 17 November 2015, when the gold deal was mentioned, and again in November 2016, three days after visiting Trump. The disclosures raise questions as to whether he participated in or profited from the proposed mining agreement with Siman Povarenkin, a Russian businessman introduced to him by the ambassador, and whether he passed on any valuable political information in the three meetings.

How did the emails emerge?

The emails from Banks and key associates were collected by the journalist Isabel Oakeshott, who knows Banks well. She was the ghostwriter of his book The Bad Boys of Brexit, a diary of the period leading up to the EU referendum, and collected the emails as part of background research at the time.

Oakeshott said she only gradually appreciated their significance and was planning to publish them at a later date as part of a separate book she had been working on with the Conservative donor Lord Ashcroft about the “state of the British armed forces”. She said some of her emails were hacked, but this has been denied by others who had obtained them. They were leaked first to the Observer, and then, seemingly with Oakeshott’s approval and Banks’s acquiescence, to the Sunday Times.

What happens next?

Banks and Wigmore, who was present or involved in many of the meetings with the Russians, are due to give evidence to a select committee on Tuesday morning. They had suggested on Friday that they were not going to appear, but as the emails emerged, they changed their minds.

MPs on the digital, culture, media and sport committee, who have the protection of parliamentary privilege, had been expected to focus on Banks’s links to Russia, including the provenance of his wealth. He is also subject to an Electoral Commission inquiry into the “true source” of his donations. Leave.EU has been fined £70,000 for accounting irregularities.

The organisation’s chief executive, Liz Bilney, another Banks associate, is under police investigation. Theresa May has said if there are any allegations that need investigation she is sure “the proper authorities will do that”.

Did Farage know about the Russian connections?

There is nothing specific in the emails about Farage’s knowledge of the additional Russian contacts. But they will raise questions for the former Ukip leader to answer. Farage has previously said Vladimir Putin is the world leader he most admires.