Ab Fab was back with another so-so offering from Jennifer Saunders and Joanna Lumley, who never look tired in their respective parts, even if their scripts are occasionally lacklustre.

You can tell Saunders is missing her skits with Dawn French, because there were flashes of some very F&S-like sketches here, including an apparently pointless trip to the beauty salon, where a not-very-funny therapist took shot at Eddie's pampered life.

For a series that so often mocks the nepotism of the middle classes, there followed a lot of bit part-appearances by members of Saunders' daughter Beattie Edmonson's comedy troupe Lady Garden, but we'll skim over that.

After Eddie's hilarious attempts at speaking Danish in the Christmas episode, there were some slightly less amusing attempts to speak French and after the winning cameo from Sofie Grabol, there were slightly less endearing cameos from Emma Bunton, Lulu and La Roux.

Still, as the cast touched on everything from iPads to interns, there were enough funny moments to whet viewers' appetite for the Olympics special that will air later in the year.

Previewers have been asked not to reveal which of the characters has been away "doing bird" (in Patsy's words), which makes writing about the first new Ab Fab episode in six years a little bit on the tangential side. Not to worry, it's a gem, embracing such intervening technological advances as iPads (Bubble tries to draw on hers) and Twitter. Eddie (Jennifer Saunders) is ballooning ("not even the credit crunch can tighten your belt"), Patsy (Joanna Lumley) decides to claim her pension - if only she can find evidence that she exists - while applauding the summer riots ("I love a bit of extreme shopping"), and Bubble (Jane Horrocks) gives a bravura one-woman summary of the royal wedding. All that and a short but sweet cameo from Sofie Grabol, Sarah Lund in The Killing - this is the first and best of the three, new, 20th anniversary episodes.

The return of Ab Fab was always a bit of a worry; the first three series were excellent, but in the post-Heat landscape, their satirising of celebrity just didn't have the same bite. Thankfully this is a return to form. Fame moves so quickly even Eddie can't keep up - "there's a new disease called Kardashians" - and as a result the comedy here is more straightforward, focused and funnier. Look out for a brief guest appearance from The Killing's Sofie Grabol.