The theme tune to the 2009 series (S1).
And the theme tune to the 2010 series (S2).
[Webmasters Note: there's no real reason for this theme tune to be here, other than I like it! Being a fan of the (late) Leonard Rossiter's Reginald Iolanthe Perrin, I liked that theme tune a lot and was delighted to find they'd kept the original and "brought it up to date"! I suspect it violates a load of copyright and media laws, so if you're not happy with it being here, please contact me and it'll be removed.]