Tony Blake (Adam Faith) is an aspiring writer who lives with other artistic types in London, but it appears his hopes may be dashed as his latest manuscript on the Loch Ness Monster is still with the publishers and has been for some time. Then one day a Mr Slate (Clive Dunn) arrives at the building he calls home and makes his way up the floors, each containing an individual Slate regards as a nutter, until he gets to Tony at the top. It's bad news, alas, he is returning his book because the subject is not selling these days, nobody has seen the monster in years and interest has waned. Tony is crushed, but then his housemates give him a brainwave: if there have been no sightings, how about he manufactures one?
What a Whopper! is an example of the sort of lightweight vehicle pop stars were placed in during the nineteen-sixties, they couldn't all be Privilege, so most were daft comedies though this had an interesting provenance in that it was penned by Terry Nation, showing an interest in outré matters a couple of years before his script for Doctor Who that invented the Daleks kicked off a pop culture phenomenon that lasts to this day. This was a far more modest affair, a cheery, silly comedy that asked nothing of you but you be entertained for an hour and a half, although there appear to have been a number of grumblers who would be asking for their money back at the time if they thought they could get away with it.
Actually, if you were in the mood for something frothy then you could do a lot worse. Material such as this was described as a timewaster more often than not, but there were a few laughs if you were in an indulgent mood, largely obvious ones yet occasionally a genuine moment of humour rose above the general goodnatured idiocy that passed for a plot. It was not a film short of acting or comedic talent, as while Faith was yet to prove himself as a thespian (that would come later, mostly on television with series like Budgie or Love Hurts), he was bolstered by some of the better performers of the day, starting with his housemates who included Terence Longdon and Charles Hawtrey, both of whom had Carry Ons in their CV.
Also there was Carole Lesley, a briefly popular starlet who just had one more movie in her career before she was dropped and sank quickly into obscurity before the news arrived that she had committed suicide over ten years after she had last graced the screen, a sad but even sadder, not untypical end to the more decorative actress of her type. Here she was the dumb blonde of many a joke, but she definitely made the role sparkle, and this may be the film she was best known for given its airings on television. Once Adam, Terence and Carole venture up to Loch Ness (in a hearse, with her screen father Freddie Frinton pursuing in his accustomed drunk act), they pick up hitchhiker Marie France (yet another would-be Brigitte Bardot) and wind up in Sid James' hotel by the water, getting mixed up with his salmon poaching scheme.
What they are there for is a scheme of their own where they go to great lengths to create the illusion of a monster, with a sizeable model, a loudspeaker and tape player for roaring sound effects, and some clawed feet that they will use on the shore to make it look as if Nessie has been plodding about (though isn't that more like what the Yeti would pass off as evidence of its existence?). Meanwhile there was a lot of running around to no particular purpose other than the illusion of forward motion as far as the plot was concerned, but everyone came across as enjoying themselves, well aware of how ludicrous this was, from a guest appearance for Spike Milligan to Terry Scott as a police sergeant. If you hated fun, this would assuredly not be for you, however there was something irresistible for a group of vintage comedy fans about a film that - spoiler - ended with the actual Nessie making a guest appearance and winking at the camera. Yes, it was far from sensible, but such unpretentious amusement was by no means worth scathing, even with that "memorable" theme song. Oh, and director Gilbert Gunn was a Scot, which defused the broader gags about his homeland. Music by Laurie Johnson.