The ‘posh boy’ comic will be playing the part of Phil Smith, junior adviser to the Shadow Tory Minister – the Opposition counterpart to Olly, as played by fellow stand-up Chris Addison in the previous series.
Smith will also be writing a future episode of the political satire.
The former Chortle award-winner has been working with series creator Armando Iannucci as a writer on the likes of Charm Offensive, but apart from a brief appearance on Time Trumpet this will be the first time he has worked with him as an actor.
Smith said: ‘It's a real thrill, although playing a terminally single, Eighties-obsessed, Lord Of The Rings fanatic will be a bit of a stretch, I'm hoping I can step up to the plate.’’
The Christmas special of the BBC Four and BBC Two comedy revolves around the Opposition, while usual star Chris Langham defends himself against child sex charges.
Will Smith is performing his Edinburgh show How To Be Cool at London's Arts Theatre on December 8 and 9. Click here for tickets
