The pair join the previously announced Russell Tovey, Gugu Mbatha-Raw, Jemma Redgrave, and Alexander Devrient.
Ruth Madeley is now confirmed to be reprising her role as UNIT's scientific advisor Shirley Anne Bingham in the spin-off.
Though fans might have anticipated Shirley's appearance in The War Between The Land And The Sea, the second new cast member is rather more surprising...
Colin McFarlane will also appear in the series as General Austin Pierce, a role he last played in the 2009 miniseries Torchwood: Children of Earth – 15 years ago.
Good to see Madeley back on screen! Her replacement in the recent season by Lenny Rush did give us another memorable UNIT character, but I'm looking forward to see more of Shirley.
Now, my memory of "Children of Earth" is a bit rusty, but iirc General Pierce will probably be wary of invaders from another world after that experience... We can hope that is the reasoning for his inclusion in this storyline?