"The last series we did, the [then] controller got in a panic and cut some things at the last moment, which really pissed me off," Harry Enfield told the Daily Telegraph, explaining their reluctance to commit to another series. "We had this father/son/grandson trio with their dog. All were totally feral. After the BBC signed off the entire series, the Jimmy Savile thing happened, and everyone panicked. The grandson was played by a boy who at the time of filming was, I think, 15 years and 10 months. There was a bit of harmless post-watershed-style swearing in one of the sketches, but the BBC decided to cut not only that sketch but all five in the series. It was nuts, and it left all our shows short and their structure unsatisfactory."

My 10 favourite Harry & Paul sketches

When everyone is quick to call time of death on the sketch show, the self same people didn't even realise that Harry & Paul were keeping the medium firing on all cylinders.

"Their comedy is challenging and bold" sing the massed choirs in the Soviet-style title music, but it isn't really. It's old-fashioned and crude, but there are moments of well-observed madness that make it lovable. What is challenging and bold is making the sixth episode of series four no more than a compilation of sketches from series three, two years ago. So say hello again to Northern Relief, a telethon organised by the Royal Society for the Protection of Northerners and one of the duo's best 1930s spoofs, entitled The Original When Harry Met Sally.

It's fair to say Harry Enfield and Paul Whitehouse have overmined the black-and-white movie seam in the latest series of Harry & Paul. But I'll happily forgive them that particular obsession. Because their gutting of Ricky Gervais last Sunday was as merciless as their On The Buses meets Sherlock sketch was inspired. If you're quick you might still catch them on iPlayer.

Tonight there's the painful sight of Harry and Paul not just missing a comedy open goal but skying the ball into row Z. They open with a sketch making fun at the expense of Ricky Gervais, mocking his sheepish grins, his self-conscious looks to camera and so on. But the impressions are nowhere near good enough, so instead of our biggest comedy star getting taken down a peg or two by a pair of elder statesmen, it all rings a bit hollow. Shame.

Elsewhere, I Saw You Coming has opened an artisan bakery and the posh surgeons, Charles and Sheridan, discuss video games.

More old-style sniggers from Harry Enfield and Paul Whitehouse, the best of which come in the opening sketch in which the duo reimagine themselves as Ricky Gervais clones, with a "celebrity" appearance by UKIP leader Nigel Farage. It's a mixed bag, but a mirthful moment comes with Sherlock Holmes as seen through the lens of On the Buses.

No one would argue Harry Enfield and Paul Whitehouse are at the peak of their powers these days but boy, when they're on song they still deliver the laughs. Tonight there's a wonderful running gag involving characters firing AK-47s in the air to celebrate good news. It's simple, childish and great fun. The same can be said for this week's "When Life Was Simpler" sketch, where a clubbable 1930s gent decides to get married at the weekend. ("She looks nice, I'll marry her!" he says equably.) And I'm starting to love indecipherable trainer Podraig - another of Whitehouse's brilliant burbling flights of fancy.