A spectacular tour de force of an episode, never before has the ending of a British television programme been so perfectly executed.

We can’t imagine we were the only ones who saw Elena Gavrik’s turn to villainy coming ever since the ending of Episode 2, and if we have one complaint about this final episode it would be that Elena’s false “confession” was a terrible move, strategically. She could have said nothing and the failure of the Russian aircraft to respond to UK air traffic control probably would have resulted in it being shot down anyway.

We’re also still struggling to understand what the point of Sasha Gavrik’s character was, especially considering the revelation that he is not, in fact, Harry’s son. Despite Tom Weston-Jones’ strong performances (and The Hair), Sasha was impossible to sympathise with, and, if anything, a little irritating, with his only real relevance to the main story ultimately being that he is the one that initiates the string of horrifying events that serve as the episode’s conclusion.

But enough with the obligatory criticism, because despite its trivial flaws, the final hour of Spooks is easily one of its finest. The central plot regarding the “highjacking” of a Russian passenger jet and Elena’s interrogation by Section D was entertaining, if not a little unoriginal, but the episode, and indeed the series, was saved by what is surely one of the most heartbreaking endings to a television series ever.

The realisation that Harry and Ruth weren’t going to get the happy ending they’d both been hoping for was easily the saddest moment in the show’s ten year run, a scene that was subsequently topped only moments later when Harry sees the names of all of the agents that have died over the years because of decisions he had made, with Ruth’s name at the end.

The final scene, where Harry walks back into work, sits quietly pontificating, before picking up the phone and getting stuck into another case, was the icing on the cake. After years of build up, the climax of the love story between Harry and Ruth is perfectly pitched. At no point have we felt that the show’s action and weekly stories have been compromised by the romantic storyline.

Indeed, themes of loss and the inherent cruelty of a career in national security have been expertly woven into many episodes over the years, but particularly this series, with Episodes 2 and 4 immediately springing to mind.

Resultantly, the show’s closing moments are genuinely affecting and, far from feeling forced, are frighteningly real. Harry finally faces the tragic consequences of his career that he knew to be inevitable, but unable to do anything else, returns to work, a broken man.

Both Nicola Walker and Peter Firth delivered career-defining performances in the episode’s closing moments, with Ilya Gavrik (Jonathan Hyde) and Elena (Alice Kruge) also expertly realised by the show’s cast earlier on; Elena’s violent murder being a particular highlight.

Some will undoubtedly be disappointed that the ending wasn’t a happy one, but as the lead writers hinted in our recent interview, such a climax just wouldn’t have been in keeping with the show’s legacy; it wouldn’t have been Spooks. We’re just gutted that it has to end at all.

Aired at 9pm on Sunday 23rd October 2011 on BBC One.

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