"We were aware of the danger of alienating our fans," he acknowledges. "But I promise you that in every episode of Families at War there are 10 minutes that are absolutely bonkers. We're not slipping into Noel's shoes."
It is true that, even at its most self-consciously wacky, Noel's House Party would never have dreamt of some of the stunts Vic and Bob have devised for their guests on Families at War. In a contest refereed by Alice Beer and adjudicated by a jury of 12 (who may consist of jockeys, shoe-shop managers, clerics or bearded men), Reeves and Mortimer each champion one family in a series of such absurd challenges as: limbo dancing while milking a cow; waltzing with a showbiz pig; doing gymnastics in Jimmy Nail's living room; or power-jogging with a singing Leo Sayer on your back.
The winning family will then direct The Spider (played by either Vic or Bob in an eight-legged costume) to pluck glittering prizes, such as the inevitable cuddly toy, from the line-up displayed in The Cubiscus. Very surreal, very Vic and Bob, very not Noel.
Whatever Reeves and Mortimer do - sketch show The Smell of Reeves and Mortimer, panel game Shooting Stars or game show Families at War - their weird and wonderful trademark is indelibly stamped on it. But Mortimer refutes the charge that this will be too out-and-out bizarre for an early- Saturday-evening slot.
"There's always a bit of sense to the challenges," he argues. "We've got a fella who does a decent Elvis, but we also noticed that he's a very keen fisherman. So we're building two riverbanks in the studio, and, in his Elvis costume, he's going to sing `Always On My Mind' while at the same time trying to hook beefburgers with his fly-fishing rod. It takes quite a lot of skill. We've also got a woman who sings beautifully, but we found out during rehearsals she can do a very good impression of a dog barking. So on the show she'll be performing a classic hit song, but with barking in it as well."
So this is what the late 20th century has brought us to: the ironic game show. "People will say it's ironic," Mortimer concedes, "but some of the acts are terrific. All we're trying to do is re-create the kind of show we liked to watch ourselves as 12-year-olds. We're not doing loads of takes, or being fraudulent or contrived. We're getting back to Light Entertainment basics. We like the idea of families sitting down to watch something together at six o'clock on a Saturday night. Family telly, to us, will always mean Blankety Blank. This is just our version of it."
Mortimer hopes to change the whole image of a slot which for too long has been associated with such icons of naffness as Jim Davidson and Bruce Forsyth. "People have been saying to us `What are you thinking of?' But wouldn't it be great if the show on BBC1 at six o'clock on a Saturday was also the funniest show on telly? I wish Paul Whitehouse Eddie Izzard, Steve Coogan and Harry Enfield were on at that time. Perhaps if we have a mild success with this, it will encourage those people to give it a go."
For all his enthusiasm, Mortimer is conscious that Families at War may fall foul of those same critics who continually carp that they "don't get" Vic and Bob. "Some people might take this as odd," Mortimer admits. "But I think it's just funny. When some people watch us, they always say `What's going on?' They think we're impenetrable. But I think we're just slapstick jokers. Hitting each other with frying pans is the oldest joke in the world. We're just a couple of clowns." Whose big top, I'm glad to say, is pitched on a different planet from Crinkly Bottom.
`Families At War' is on BBC1 at 5.45pm tonight