•
Tim Pigott-Smith as Chief Constable John Stafford (Series 1–3) •
Martin Shaw as Chief Constable Alan Cade (Series 3–5) • Karen Archer as Assistant Chief Constable / Acting Deputy Chief Constable / Acting Chief Constable Anne Stewart (Series 1–4) •
Eamon Boland as Detective Chief Superintendent Jim Gray (Series 1–3) •
Stuart McGugan as Detective Superintendent / Detective Chief Superintendent / Acting Assistant Chief Constable Sean McCloud (Series 3–4) •
Gillian Bevan as Detective Superintendent Rose Penfold (Series 5) •
Tony Caunter as Deputy Chief Constable / Acting Chief Constable Arthur Quine (Series 1–2) •
Bosco Hogan as Deputy Chief Constable Wes Morton (Series 5) • Dean Lepley as PC Jack Sayers (Series 1–5) •
Brian Bovell as PC Charlie Webb (Series 5) •
Michael Cochrane as Nigel Crimmond (Series 1–5) • Gillian Martell as Diane Lewis (Series 2–5) •
Judy Loe as Dr. Elizabeth Stafford (Series 1–3) • Ross Livingstone as Tim Stafford (Series 1–2) •
T. P. McKenna as Colin Fowler (Series 2–4) •
Julian Glover as Andrew Blake (Series 5) ==Series overview==