Holmes is consulted by Sir James Damery (Ballard Berkeley) who is acting for an unnamed (but illustrious) client. Violet de Merville (Jennie Linden) is engaged to be married to Baron Gruner (Peter Wyngarde). Gruner has an evil reputation (several deaths, including that of his former wife, can be laid at his door – although he’s never actually been convicted of anything).

Many people have attempted to warn Violet off, but she is completely besotted with Gruner and won’t hear a word against him. Holmes agrees to act but Gruner is a very dangerous man, so by opposing him Holmes will put his life in danger …..

The Illustrious Client was one of Conan Doyle’s final Holmes tales (originally published in 1924). The majority of stories adapted for this series tended to be drawn from the earlier runs (which are generally considered to be stronger) but since this one has a formidable villain it’s no surprise that it was selected.

Peter Wyngarde (later to play the dandy writer and sometimes detective Jason King) is compelling as the malevolent Gruner. Yes, his accent is a little distracting, but he manages to display such a sense of menace that you can forgive him for that. Gruner’s relationship with the unfortunate Violet is an interesting part of the adaptation – he makes no attempt to hide his cruel streak, instead he seems to revel in mistreating her (and she either enjoys it or is so blinded that it simply doesn’t register).

Linden (who would play Big Screen Barbara later that year in Doctor Who and the Daleks) exerts an icy control over herself whereas Rosemary Leach (as Kitty Winter) barely has any control at all. Kitty was one of the Baron’s many previous conquests – used and then tossed aside. She agrees to help Holmes in his attempt to make Violet see exactly what sort of a man the Baron is, but she also has her own agenda.  It was one of Leach’s earliest television appearances and she’s very watchable as the bitter and damaged Kitty.

There’s plenty to enjoy in this one. Holmes and Watson take a trip to a music hall to visit one of Holmes’ underworld contacts. Although it’s only a studio set, it looks very impressive and clever camera angles manage to hide how small it is (and how few people are actually there).

Holmes and Gruner face off in a spellbinding scene (lifted virtually verbatim from the original story) which is a perfect showcase for both Wilmer and Wyngarde. The only thing that slightly spoils it is some rather wonky camerawork at the start (which was something that tended to happen in VT dramas of the period – a pity they couldn’t have gone back for another take).

Nigel Stock might be largely used for comic relief, but he still manages to instill Watson with a certain dignity. Although it must be said that one of the drawbacks of making his character seem a little dense is that when Holmes asks him to swot up on Chinese pottery (so he can distract Gruner, whilst Holmes burgles his study for incriminating evidence) it’s difficult to believe that he’d be able to pull it off.

But he does pretty well and the scene between Stock and Wyngarde is another good one – Wyngarde is arrogantly playful, whilst Stock falls back on bluster when he realises he’s on shaky ground.

Like some other Sherlock Holmes stories, there’s no real mystery here – rather the story revolves around the different characters and the way they interact with each other. And thanks to the first-rate guest cast (headed by Peter Wyngarde and Rosemary Leach) it’s a memorable fifty minutes.