Where, exactly, has Ambassadors gone wrong? The idea, sending blundering diplomats to a chaotic post-Soviet state, is sound, while the casting - with Mitchell & Webb as inept and smug respectively - is tried and tested. The fault lies in the tone: Ambassadors demonstrates, like so many others before it, just how difficult a comedy-drama can be to execute.

Tonight's final episode is another slice of ripe characterisation, featuring Michael Smiley's crack government interrogator and Natalia Tena as the Tazbek President's spoilt, tarty daughter. There are promising situations too, as a power cut and an ill-advised tryst leave Keith (Mitchell) and Neil (Webb) looking distinctly compromised. But the whole simply doesn't hang together - infuriating, given the talent involved. Ambassadors may need a rethink before serving another term.

Mitchell & Webb: The funny old world of foreign affairs

David Mitchell and Robert Webb are back on our screens in a new BBC Two series, Ambassadors. Diplomacy is a rich source of such comic material, so it's surprising no one has tried to cover it before, they tell James Rampton.

Can Mitchell & Webb help the Foreign Office's image?

The Foreign Office is turning to satire to improve its image after assisting David Mitchell and Robert Webb to create a new BBC comedy series which portrays the fraught world of the diplomatic service.

Are Mitchell & Webb anything like their characters?

The actors reveal their dating tips and mishaps, first kisses, romantic gestures and how they knew they'd met "the one".

A quick chat with David Mitchell and Robert Webb

TV & Satellite Week magazine caught up with Mitchell & Webb to find out where it all went wrong...

As Mitchell & Webb once pointed out, it's in the nature of the sketch show to be patchy. And this new C4 offering combining sketches with impressions maintains that archetype. Starring Morgana Robinson and Terry Mynott, Very Important People mostly trains its sights on the banalities of celebrity culture. It's a risky strategy; these are the softest of targets - is it necessary to take the piss out of Amy Childs and Joe Swash when they're already giving it away by the bucketload? Still, VIP does hit the mark often enough to suggest that these are talented performers, even if their material needs to challenge them more. Brian Cox is good-naturedly skewered for his vanity - gazing at stars, boasting about his jacket and bullying his hapless cameraman along the way. And the sketch in which Frankie Boyle is observed in his natural habitat (the book signing, searching for news of murdered children on the internet) by David Attenborough at least has the advantage of feeling like a hunt for some bigger game. Far from perfect, but worth keeping an eye on.

That Mitchell & Webb End of Series Quiz

As the producer of That Mitchell and Webb Look I often imagine what it would be like to have thousands of fans clamouring for an end-of-series-four quiz.