www.bbc.co.uk/news/uk-politics-64362640
Mr Johnson was reported to be in financial difficulty in late 2020.
The Sunday Times says multimillionaire Canadian businessman Sam Blyth raised with Mr Sharp the idea of acting as Mr Johnson's guarantor for a loan. It is not clear where the loan money came from.
Mr Sharp - a Conservative Party donor who at the time, was applying to be the chairman of the BBC - contacted Simon Case, the then-cabinet secretary and head of the civil service.
According to the paper, Mr Sharp, Mr Blyth and Mr Johnson had dinner together at Chequers before the loan was finalised, although they deny the PM's finances were discussed then.
Former Goldman Sachs banker Mr Sharp was announced as the government's choice for the new BBC chairman in January 2021. The role is recommended by the culture secretary and the prime minister.
The BBC chairman heads the board that sets the corporation's strategic direction and upholds its independence.
I think this was an episode of Yes Prime Minister - where someone helps out the Prime Minister and gets the Chair of a quango.
It's getting very hard to tell the difference nowadays.
And now the Chair of the BBC has strong ties to someone who could still have been Prime Minister, had he not had to resign