A very quick guide to Nadhim Zahawi

Nadhim Zahawi is facing calls to quit as a government minister and chairman of the Conservative Party amid a row over his taxes. If you have not been following the story, here's what you need to know about why he's under pressure.

Born in Baghdad to an influential Kurdish family in 1967, he fled Iraq with them at the age of nine. He grew up in Sussex and went to university in London, before following his father into business. He later worked for ex-Tory MP and bestselling novelist Lord Archer during his failed campaign to become London mayor.

As an entrepreneur, he once set up a firm selling merchandise for the Teletubbies TV show. It's thought he made the bulk of his fortune, estimated at up to £100m, setting up one of Britain's best-known polling companies, YouGov, before becoming an MP.

Prime Minister Rishi Sunak made him Conservative Party chairman in October, in charge of fundraising and election campaigns. But his highest-profile job was being chancellor - the UK's finance minister - for the final two months of Boris Johnson's time in Downing Street.

He's admitted making a payment to HM Revenue and Customs to settle previously unpaid tax. He said this was related to how YouGov was set up, specifically an "error" over the number of shares given to his father. He is facing accusations he tried to avoid tax and has now had to pay it back with a fine.

He says the taxman accepts it was a "careless and not deliberate" error. But he hasn't explained how much he paid back, or why. The BBC understands he paid around £5m in total, including a penalty. An official adviser to the PM is looking into whether Mr Zahawi broke the rules on behaviour for government ministers. If he has, it will be up to Mr Sunak to decide whether to sack him or not.

Mr Sunak says launching the investigation means he is following "proper due process". But Labour and other parties that oppose the government say Mr Zahawi should resign now - or the prime minister should sack him.

The BBC understands Mr Zahawi made the tax payment last year, while he was chancellor and therefore in charge of the tax system. Mr Sunak is facing calls to explain exactly what he knew about Mr Zahawi's tax settlement before making him Conservative chairman.