The 42-year-old plays debonair news reader Hector Madden in the BBC drama, but said that in the new series - which has just started shooting - he is becoming more like loveable rogue Jimmy McNulty, the cop he became famous for playing in crime show The Wire.
West laughed: "Well I thought I was playing Carey Grant you see and it turns out I'm just playing Jimmy McNulty again!"
He added: "My character takes quite a dive in terms of his health and everything else, that's always interesting to play so I'm glad about that."
Romola Garai, Ben Wishaw, Anna Chancellor, Julian Rhind-Tutt and Oona Chaplin are all due to return in the new series of the critically acclaimed BBC show about a 1950s newsroom, written by Abi Morgan.
Capaldi will play Randall Brown, the eccentric new head of news and Burke will play Bill Kendall, a charming producer who Garai's character Bel finds herself attracted to.
Tointon will play a Soho club hostess who befriends Hector, as he becomes unsettled by his wife Marnie's desire to have her own career.