It's been a rum little monkey, Family Tree (BBC Two), full of bad jokes and oddball characters.

But, as Chris O'Dowd's Tom Chadwick dithered over his future in a 'there must be a series two'-type cliffhanger, there was a surprising melancholy to waving farewell to this curious bunch at the airport.

The satire on the whole Who Do You Think You Are? TV franchise was a tad overcooked - surprisingly so, given the pedigree of writer/director Christopher Guest - but there was just enough wit scattered among the branches of Tom's extended clan to make up for the feeling that no family could contain this many nutters.

'Do you find that being around books makes you more clever?' Tom asked potential squeeze Ally. 'No, it makes me feel like all the ideas have been written already,' she replied. They were made for each other.

And Fred Willard's Al Chadwick had a camp hoot with a stream of bad gay jokes. 'How do you fit four gay men on one bar stool?... turn it upside down!' So wrong.

Watching this new Christopher Guest sitcom is a peculiar experience. For example, the pieces to camera can look like a hackneyed device, worn out through over-use. But then, if Christopher Guest can't utilise pieces to camera from his characters, who can? For a particular kind of arch, absurd, self-aware comedy, he wrote the rulebook.

This feels like a very new venture for Guest. Not only is Family Tree his first TV project, but it's more plot-heavy and open-ended than his film work: the box of family treasures given to laconic lost soul Tom Chadwick (Chris O'Dowd) could be the passport to as much digression, misadventure and silliness as Guest and the cast fancy, as Tom follows his familial trail through Britain and America.

The Family Tree ensemble also contains Michael McKean, Nina Conti, co-writer Jim Piddock, Tom Bennett and eventually, such mainstays of Guest's films as Fred Willard. So, even if this opening episode feels slightly low-key, it seems reasonable to assume that we're in safe comedic hands.