They'll be joining the previously announced leads, Matt Berry, Susan Wokoma and Freddie Fox.
The new six-part comedy follows Detective Inspector Rabbit, played by Matt Berry, a hardened booze-hound cop in Victorian London.
He's aided and abetted by his new partner Wilbur Strauss (Freddie Fox) and the country’s first female police officer, Mabel Wisbech (Susan Wokoma), as they bring justice to the streets of the east end.
Within the turmoil of the Whitechapel police station, Alun Armstrong plays Chief Inspector Wisbech who suffers two ways, as Rabbit’s boss and Mabel’s father. And Paul Kaye plays Rabbit’s nemesis, D.I. Tanner.
In addition to the announcement, Channel 4 have released some new images from the upcoming series which show Keeley Hawes as the mysterious Lydia, Sally Phillips as Princess Juliana of Bulgaria and Jill Halfpenny as Rabbit’s ex, the deadly Flora.
Speaking about joining the series, Keeley said “It’s great to be working with Matt, Susan and Freddie on such a brilliantly original show. Lydia is such an enigmatic character. It’s been a thoroughly enjoyable, bonkers experience.”
Sally added "I can report that there is literally nothing more pleasurable than playing a haughty, 19th Century, pansexual, Bulgarian autocrat with access to guns. I may have peaked.”
And Jill said “I’m thrilled to be a part of Year of the Rabbit. It's an amazing creative team and I’ve had the best time making it.”
The series is directed by BAFTA-nominated Ben Taylor (Catastrophe, Sex Education) and written by Emmy and WGA Award-winners Andy Riley and Kevin Cecil (Veep, Black Books), with additional material from Matt Berry.
Further cast includes David Dawson, Ann Mitchell, Alistair Petrie, Matthew Holness and Craig Parkinson.
Year of the Rabbit airs later this year on Channel 4