Downing Street's new Chief of Staff, Mark Fullbrook, is not a stranger to politics. He's been the "backroom boy" behind many political campaigns around the world, including Boris Johnson's successful Mayor of London campaigns and President George Bush’s unsuccessful re-election bid in 1992. But, until now, Mark Fullbrook has kept his names out of the headlines.

That changed when it was reported that Fullbrook had been questioned as a witness in an FBI inquiry into alleged electoral bribery in Puerto Rico. Then, this week, he became headline news when it was revealed his Downing Street salary was being paid through his own lobbying firm. The publicity comes at a bad time for Prime Minister Liz Truss who is facing economic turmoil following the Chancellor's mini-budget.

So, who is Mark Fullbrook and why do we know so little about him? Mark Coles looks at the life of an influential, yet unheard-of, political figure.

Presenter: Mark Coles