Again, an oddly surreal-comedic quality to this story. However the plot premise is plain ridiculous: I don't care what Cowley says: the KGB wouldn't suddenly decide to murder dozens of ex-security service personnel on the off-chance that they might all meet up one day and discover the identity of a double agent between them. No, that just doesn't stand up, IMHO.

And the overall storytelling is full of plot holes, too. For example if the KGB agent decided to check out Doyle then why didn't do the same with Bodie? It's never explained why he suspects Doyle of being an infiltrator.

And how on earth does Miss Walsh, using some drawing pins and brightly-coloured wool, come to her conclusions? Again, these are simply taken at face value.

And it seems a bit too convenient that Williams hides himself in the car, petrified by the thought of having to assassinate somebody.

There are several other things but if I discussed them that would spoil the episode for those who have yet to see it.

However I'm now going to surprise you all by stating that 'Spy Probe' ranks as one of my favourites from the later years of The Professionals. What is good is that the characterisation and interplay between the two main villains are funny. I liked old Ferris and Twig, even though they were merciless killers. When they are together doing all the planning, their banter is tinged with humour (Ferris calls his fat friend 'Twiggy'). Yet when it comes to them actually killing people (eg the guy on the bridge) their facial expressions are those of hardened, ruthless murderers. Immediately after the shooting, though, Ferris returns to his irreverent self.

In fact Barry Stanton (previously briefly seen as Frank the Mercenary in 'The Madness of Mickey Hamilton') as Ferris, the sweet-guzzling assassin really is excellent here. ("I thought he was sweet!" / "Eh?!!" / "Yeah - all the sweets he eats!" - oops, this little gem was inexplicably culled from the G+ showing.) Ferris and Twig would have worked wonderfully in The Avengers. Indeed Clemens' and Fennell's earlier production loved to satirise popular culture and we see a touch of this with the hotel scenes clearly "stolen" from The Thomas Crown Affair.

The episode is fast-paced, has loads of well-orchestrated and photographed action and a healthy dose of comedy, too. For these reasons, I've marked Story a little higher than perhaps it deserves.

Nice directorial touch with the traffic lights in the early scenes.

Love the daft scene where the lads drive their Capris at each other head-on to see how close they can stop without crashing!! ("Three inches?" / "No – four."). Don't try this at home, kiddies! See Locations section.

For more camp, black humour check out Ferris' interrogation scene:

Ferris: "Where are you taking me?"
Doyle: "Don't worry... it's soundproof."
Ferris to Cowley: "What does he mean 'soundproof'?"
Cowley, perfectly straight-faced and levelly: "He means... [slight pause for effect] ....nobody will hear your screams." Then, to Doyle: "OK, get on with it."
Ferris: "What's he doing?"
Cowley: "Filling a bath... or, at least, half-filling it: we don't want to make a mess."
Doyle picks up a telephone: "Send Sparks down with his box of tricks."
Ferris, terrified: "What are you going to do?"
Doyle, donning industrial rubber gloves: "Give you a bit of a shock. Might jog your memory."

Forget the plot, watch the action, listen to the dialogue - all great fun!

All the dock scenes were filmed at Victoria Deep Water Terminal.

Keen to keep ratings up right until the end of the series, LWT originally commissioned an "open-ended" script which offered the possibility that Bodie and Doyle might succumb to watery graves in the final scene. Heavily promoted before its transmission, LWT then peformed their usual scheduling incompetence and screened the episode in the middle of the run!?!?!?!

Two years after this episode was shot, the warehouse and its dummies were used again for the Minder episode 'Get Daley'.

Paul Daneman (Dawson) had minor roles in classics Zulu and Oh! What a Lovely War. Perhaps best known for the mid-1970s espionage series Spy Trap. Last seen in Alan Bleasedale's GBH. Passed away in 2001.

Graham Crowden (the minister) starred in the university comedy drama A Very Peculiar Practice and fondly-remembered sitcom Waiting for God.

Nick Stringer (Twigg) has been a ubiquitous character actor for over twenty years, usually playing dodgy-dealer types.

Patrick Ryecart (Williams) appeared in several episodes of the 1979 TV adaptation of Dick Turpin, the 1980 David Wickes film Silver Dream Racer and a couple of episodes of the Young Indiana Jones TV series. Still pretty active in the acting fraternity but has never made leading man material on TV or film. He was married to Marsha Fitzalan, previously seen in 'Wild Justice'.