Time to get out the hankies, obviously dusting them first for fingerprints. After 10 series of poker-faced shenanigans at the heart of the British security services, Spooks finally signed off for good last night, and from the outset, it was clear that stakes were high.

Love's long-unexpressed service stalwarts Harry and Ruth were actually discussing leaving the Grid, to finally put their vigil to bed and, I don't know, watch Corrie in a seaside cottage with a green door. Would they reach their rural idyll? Well, all I'm going to say is that the scriptwriters have never been shy to kill off any of its main characters in favour of a narrative arc. Why would they stop now?

In many respects, Spooks finally did what it has forgotten to do recently, and something it always used to do best - that is, have a bizarrely small team of people - all equally proficient in the very different skills of intelligence, government liaison and field work - deal with an unprecedented random and enormous threat. In this case, it was an extremist bunch of Russkies intent on breaking down the budding relationship between the Soviet and British blocs.

I've always been impressed by a) how Spooks scriptwriters stay in step with topical events - no al-Q'aeda cells here, that's so 2009 - there's even chat about St Petersburg University, which is painfully topical if you happen to be a suspected Westminster researcher, and b) how the same MI5 operative can be speaking fluent Russian, dressed as waiter, unlocking a brief case with a paper clip one minute, then swapping his serviette for a balaclava and shooting a man in the kneecap (so sanguinely British) from a mile away the next - a very reassuring display of multi-tasking.

And it was even more reassuring to see a stony, familiar face from Series One, which seems only a bit less recent than the Cold War itself.

Last night's episode had all this going on within the ongoing story of Harry Pearce's long-ago love affair with a Russian gal coming back to haunt him. Pale, timelessly cheek-boned Elena proved to be a double agent, or triple, not entirely sure - which meant, inevitably it became personal, with Harry forced to choose whose word to believe, between the two women who have ever meant anything to him, the deceptively fragile Elena and Ruth, exactly the sort of woman you'd want next to you in this kind of crisis, or any time really.

The idea that warm, witty Ruth is "great at analysis, intelligence, not so good with people" is one of the continuing anomalies of this series that was never fully explained.

Of course, everyone got a bit over-excited, it all ended in double-dares, unblinking poker-faces trying to out-bluff each other and, where all else failed, a big jab with a bit of glass. Along with Harry, we were left to gaze at a conveniently placed memorial to all those lost over a decade of service to BBC primetime drama, and ruminate once again on the dilemma that is the backbone of this fine, sometimes silly, but always well-intended drama - that of the increasingly distant prospect of ever being both a good spy, and a happy man.

Spooks Series 10 is released on DVD on 28 November.

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