Ice Maiden

The third series introduces its most durable adversary in a Christmas Eve broadcast. "Ice Maiden" gives us Philippa Vale — the diamond thief who has never been caught, glamorous, unflappable, and about to become the recurring thorn in Bergerac's side for the rest of the series. Joanna Lumley, at the height of her New Avengers fame, plays her with a cool, amused poise that makes every scene between the detective and the thief crackle. The premise is simple: a famous diamond is to be auctioned in Jersey, and Vale — spotted by airport security — is coming to steal it. Bergerac decides to beef up security around the auction, knowing full well that she is coming and that the island is the trap.

The episode is a cat-and-mouse between two professionals who genuinely enjoy each other's company. Their first conversation, all double-talk and barbed courtesy, establishes the dynamic that would run for years: Bergerac knowing exactly who she is, Vale knowing exactly what he knows, and neither able to make it stick. Rod Beacham, who would write several of the Vale stories, builds the hour around the auction house, the alarmed windows, the shutters that come down while the diamond is present — and the impossibility of keeping a thief like Vale out of anywhere she has decided to enter. Robert Tronson directs with a light, stylish touch.

George Sewell and Michael Culver round out the guest cast, and the episode gives Lumley the best of the material — including a flash of real feeling when Bergerac mentions her father, a second-rate artist who died penniless, and she lets the mask slip for a moment before recovering it. The Christmas timing gives the broadcast a festive frame without softening the story.

It is a confident, stylish hour with a guest turn that would define a whole era of the series. Vale is not a villain to be caught but an opponent to be met again, and the episode knows it. A strong mid-season entry that opens a thread the later series would return to again and again — and proof that Bergerac's best duels were often with people who were never going to prison.