I was uncertain about the idea of a comedy about a British ambassador in an obscure eastern European country.

Would a mix of diplomacy and comedy work? And then I remembered Labour's idea of an ethical foreign policy in the 1990s. That was pretty hilarious, so maybe Ambassadors (BBC Two, Wednesday, 9pm) would work after all.

It certainly has promise. For a start, it is co-written by James Wood, who created Rev, the rather good sitcom with Tom Hollander as a London priest. It also has David Mitchell and Robert Webb in it: Mitchell as the British ambassador to the fictional Central Asian Republic of Tazbekistan and Webb as his second-in-command.

In reality, they are playing exactly the same characters as the ones they played in their Channel 4 comedy Peep Show. Mitchell is the bumbly, ineffectual, socially retarded one and Webb is the slightly sleazy, swaggery one who is also socially retarded but doesn't know it. In Mitchell's case, this means that Britain's representatives abroad are stereotyped as well-meaning but accident prone. This may or may not be true.

It wasn't the only racial stereotyping going on. In fact, the first episode was full of many broad generalisations about foreigners. Eastern Europeans need a bribe to get things done, for example, and the French will come out kicking, biting and eye gouging to get their own way.

What just about prevented this from being offensive was the fact that most of the racial stereotyping was aimed at the British characters. Particularly amusing was Matthew Macfadyen, a wonderful, changeable, attractive actor who is now inheriting all the roles that Hugh Grant used to be good at. In Ambassadors, he played a slick, slicked-down, supremely confident Tory minister who wants to secure a £2 billion helicopter deal with the Tazbeks pretty much at all costs.

Which was where Ambassadors looked like it might make some interesting points about British foreign policy, but then it didn't. A programme like The Thick Of It or Yes Minister would slap or punch home its point, but Ambassadors has a coquettish, shy approach to saying anything satirical or revealing about its central subject.

Webb's character, Deputy Head of Mission Neil Tilly, was being bribed, and there was talk about avoiding a Blair/Gaddafi-style handshake with the local politicians, and getting the balance right between being close to and distant from questionable foreign contacts at the same time. But it lacked conviction. Just when it began to circle its point, it veered off again.

This, combined with the lack of any interesting plot, meant the first episode went flabby and flat, like one of the less successful cakes on last week's Bake Off final. Mitchell and Webb are always watchable, which helps, but we were watching them doing something vaguely like the thing they did before. There is probably a place for a satire on Britain's role abroad but it needs to be fierce and brave and risky. Like one of the more successful cakes on Bake Off, Ambassadors was much too homely and nice and warm.