Everyone loves sparks flying on the chatshow circus and the best chance of a meltdown tonight looks likely to come from the wayward Britney Spears as she drops by for a chinwag with Alan Carr.

Will he ask her opinion on twerking Miley Cyrus? Also making merry with Carr are Olympic hero Mo Farah and actor Joseph Gordon-Levitt, plus music from Jake Bugg, while Graham Norton has landed Paul McCartney, Natalie Portman, Chris Hemsworth, James Corden and Katy Perry.

As usual, Norton's bookers have activated their tractor beam to draw in the best celebrities. For a start, Paul McCartney is on the couch! Our greatest living songwriter (discuss) will talk about his new album, helpfully entitled New, and give us a sample - most likely the Beatles-y title track, which sounds like a breezy relative of Got to Get You into My Life.

At the other end of the pop spectrum is Katy Perry - she has a new album out soon. And let's not forget the actors: Natalie Portman talks about her role in Thor sequel, The Dark World and if that wasn't enough star wattage, James Corden drops by.

What would have happened to John Lennon had he left the Beatles in 1962, on the cusp of greatness? We join Lennon (Ian Hart, uncanny in his third outing as the Beatle) in grey, 1991 Birmingham, scratching out a living in dead-end jobs, dispensing pithily sardonic observations and denying his mild resentment towards Paul McCartney.

In this universe, Macca's Lennon-less Beatles are dragging themselves around the low-rent nostalgia circuit after a middling career of melodic that saw them eclipsed by the likes of The Hollies.

Snodgrass (Lennon's tag for 'The Man') could have been a dismally self-regarding muso wank-off - and there are in-jokes aplenty for Fab Four obsessives. But it also works beautifully as simple human drama, anchored by a performance of thoughtful melancholy from Hart. The concept is neither overthought nor over-explained, the attention to detail in David Quantick's screenplay (based on Ian R MacLeod's novella) is stunning, and Ex-Boo Radley Martin Carr's soundtrack of affectionate pastiches completes this miniature masterpiece of disappointment and regret.

Anyone casually inferring that the title of this 90-minute documentary might shed light on the inner workings of knowing music-hall surrealist Frankie Howerd is likely to be mildly disappointed. The Lost Tapes is far more interested in his stage-and-screen career than his occasionally tumultuous private life. That said, the plethora of footage unearthed here is an absolute treat for any fan of British comedy. Bruce Forsyth, Tim Vine, Ross Noble, Roy Hudd, Galton & Simpson and the eternally youthful Barry Cryer guide us through clips ranging from Frankie's stint at Peter Cook's Establishment Club to his scenes - sadly left on the cutting-room floor - with Wendy Richard and Paul McCartney in The Beatles' Help! to footage of another musical misfire in his role opposite The Bee Gees in the regrettable promotional movie that accompanied their Cucumber Castle LP. Other nuggets include clips from 1973 Up Pompeii! rehash Whoops Baghdad and a 1976 sitcom made for Canadian TV.

Following previous docs delving into the hidden worlds of comedy greats Eric Morecambe and Spike Milligan, this profile of the Up Pompeii star promises a number of undiscovered gems. Taking in previously unseen footage, from home movies to live stand-up material, this profile celebrates the life of the comic actor whose career stretched all the way from Variety Bandbox to 1990's The Craig Ferguson Story (playing The God Of Comedy, no less). Also, a peek at Howerd's extensive correspondence, including exchanges with the likes of Laurence Olivier and Paul McCartney.

What happened to impressionists? There was a time when it was the blue-chip form of light entertainment, and no weekend or Christmas was complete without a special. But the steam seems to have gone out of it a little these days. The Impressions Show has its moments (Debra Stephenson gets that mad vamp off Dragons' Den to a T and Jon Culshaw nails Paul McCartney and Prince Charles). But all too often if you close your eyes you wouldn't have a clue who was being lampooned. It gives an impression of being entertaining, but not always a convincing one.

Jon Culshaw and Debra Stephenson offer up another 30 minutes of pretending to be other people. When the show hits home, as in a MasterChef skit where John Torode and Gregg Wallace reckon the contestants are "like cows at an abattoir", there's much fun to be had. Paul McCartney reforming the Fab Four with "all of the surviving Beatles except Ringo" and the Gok Wan wok gun also hit the mark. At other times, though, don't be surprised if your attention drifts: the show is consistently inventive without necessarily being consistently funny.

James Corden on how he bagged a Beatle for Comic Relief

James Corden is told that Sir Paul McCartney would like to speak to him. "Yeah. OK," he says, outwardly quite cool, inwardly all over the place. Then, a few days on, he hears that the former Beatle will call him shortly.

Paul McCartney tells James Corden he's too fat

Beatles legend Paul McCartney tells comic James Corden he's too fat to go to Africa in a new sketch for Comic Relief.

Heather Mills has not enjoyed a particularly good press of late, so Star Stories waded into the fray to redress the balance. Its unique take upon tabloid events cast Paul McCartney as a sadistic and cruel tyrant, egged on by his manipulative daughter Stella, cosily living in a luxurious country house called Mandalay. Heather, in contrast, is a shy and naive Geordie girl for whom her charity work is everything.

'Whose the daddy?' screams Paul in flashback, as he terrorises the other three Beatles into performing on the Abbey Road studio's roof. So great was the programme's excursion into delusional fantasy that it even suggested Sir Paul's hair was dyed.

Jokes about Mills' disability were inevitable but, given Star Stories' gleefully puerile approach, remarkably few and far between.

Star Stories serves up pretty much the same fare every week, irrespective of its subject matter, but sheer nerve, energy and clever writing has so far kept it from going stale.