| | | | Part One Slough House |
| | Jackson | Lamb | The unpredictable leader of a group of spies. |
| | River | Cartwright | A British MI5 agent. |
| | Sidonie | Baker | A competent MI5 agent. aka: Sid. |
| | Robert | Hobden | A journalist. |
| | Max | | A barman. |
| | Jed | Moody | One of the MI5 agents. |
| | Roderick | Ho | An obnoxious computer expert and former hactivist. |
| | Catherine | Standish | The office administrator and a recovering alcoholic. |
| | Min | Harper | An agent. |
| | Louisa | Guy | An agent. |
| | Struan | Loy | An agent. |
| | Kay | White | Catherine's floor mate. |
| | Peter | Judd | A rising right-wing politician. |
| | Russell T. | Davies | Welsh screenwriter and television producer. |
| | Timothy | Spall | An English actor. |
| | John | Falstaff | One of the most famous comic characters in all English literature. |
| 2 | James | Webb | An MI5 agent based at Regent's Park headquarters. aka: Spider. |
| | Diana | Taverner | The Deputy Director-General of MI5. aka: Lady Di. |
| | Charles | Partner | A double agent at the top of MI5. |
| 3 | Sam | Chapman | Head of the intelligence service's internal security force. |
| | Nick | Duffy | Head of MI5's internal affairs and tactical unit. |
| | Geoffrey | Boycott | A former Test cricketer. |
| 5 | David | Cartwright | River's grandfather. A retired MI5 officer. |
| | Kim | | A novel by Nobel Prize-winning English author Rudyard Kipling. |
| | Marjorie T. | Greene | American politician. |
| | W. Somerset | Maugham | English playwright, novelist, short story writer. |
| | Ingrid | Teary | The Director General of MI5. |
| | Tom | | Taverner's boy. |
| | Larry | | Curly's acquaintance. |
| | Moe | | An undercover agent. aka: Alan Black. |
| | Curly | | The one who murdered Moe. |
| | Hassan | Ahmed | A British-Asian student kidnapped by the far-right. |
| 6 | Roy | Jenkins | A British politician, historian and writer. |
| 7 | Wolfgang A. | Mozart | Austrian composer of the Classical period. |
| | Leonard | Bradley | A former head of the Limitations Committee. |
| | Roger | Barrowby | Bradley's acquaintance. aka: Barrowboy. |
| | | | Part Two Sly Whores |
| 9 | Isobel | Cartwright | River's mother. |
| | Dan | Hobbs | One of Nick Duffy's crew. |
| | Buster | Keaton | American actor and filmmaker. |
| 10 | Sebastian | Sleek | Robert Hobden's acquaintance. |
| | Andrew Lloyd | Webber | English theatre composer. |
| | David | Kelly | A Welsh scientist and authority on biological warfare. |
| | Dave | Spencer | A well-known American journalist. |
| | Mahmud | Gul | 2nd Desk at Pakistan's Directorate for Inter-Services
Intelligence. |
| | Nicholas | Frost | A British actor, author, comedian, painter, producer. |
| 12 | Gregory | Simmonds | A wealthy businessman with right-wing. |
| | Adolf | Hitler | German politician. |
| 13 | Gordon | Brown | Prime Minister of the United Kingdom. |
| | Bruce | Lee | Hong Kong-American actor, martial artist. |
| | Simon | Dean | A tele-salesman for a life-assurance company. |
| 16 | Daniel | Radcliffe | An English actor. |
| | Joanna | Lumley | A British actress and former model. |
