The UK's top civil servant has been asked whether any private donations were used to fund the refurbishment of Boris Johnson's Downing Street flat.

In answering, Cabinet Secretary Simon Case told a Commons committee he has been asked by the prime minister to lead a review into how the work was paid for.

It's after the PM's former top adviser, Dominic Cummings, claimed it was once planned to have donors "secretly pay" the refurb.