Alex Macqueen
From Tardis Wiki, the free Doctor Who reference
Alex Macqueen is an English actor and voice actor who has played Gabriel in the Big Finish Doctor Who audio story Paradise 5 and the Reborn Master in Dominion, Dark Eyes, Vampire of the Mind and The Two Masters.
He played Julius Nicholson in The Thick of It opposite Peter Capaldi and also appeared (as another character) in the film spin-off In the Loop.