| Name | Character | Episodes |
|---|---|---|
| Rupert Penry-Jones | Clive Reader | 18 |
| Maxine Peake | Martha Costello | 18 |
| John Macmillan | John Bright | 18 |
| Neil Stuke | Billy Lamb | 18 |
| Theo Barklem-Biggs | Jake Milner | 18 |
| Alex Jennings | Alan Cowdrey | 13 |
| Natalie Dormer | Niamh Cranitch | 12 |
| Phil Davis | Micky Joy | 12 |
| Frances Barber | Caroline Warwick | 12 |
| Amy Wren | Bethany Brassington | 12 |
| Indira Varma | George Duggan | 6 |
| Jessica Henwick | Amy Lang | 6 |
| Nina Sosanya | Kate Brockman | 6 |
| Tom Hughes | Nick Slade | 6 |
| Miranda Raison | Harriet Hammond | 6 |
| Jamie Dispirito | Jimmy Johnson | 6 |
| Adrian Schiller | Noah Zeigler | 3 |
| Peter Vaughan | 1 | |
| Owen Teale | 1 | |
| Gerard Horan | 1 | |
| Aden Gillett | HHJ Donovan | 1 |
| Fenella Woolgar | 1 |