Baroness Floella Benjamin, Sir Trevor McDonald, Reverend Richard Coles and Moira Stuart to host Countdown.
To celebrate the 40th anniversary, daytime show Countdown is set to welcome a string of new celebrity faces to the presenter's chair for a month long run of episodes.
Joining Susie Dent in Dictionary Corner will be criminal barrister and broadcaster Rob Rinder, newsreader and presenter Dan Walker, maths genius and writer Bobby Seagull and actor and presenter Christopher Biggins.
The 40th anniversary episodes of Countdown are airing this month. In November, 40 years to the day that Channel 4 started broadcasting, Paul Coia, the first Channel 4 continuity announcer who introduced Channel 4's first ever programme - Countdown - will return to introduce the show once again.