Downe comes from a long and honourable tradition of one-joke wonders, comedians who have founded an entire career on a single schtick. Need I say more than Julian Clary? The trick is to find a joke strong enough to sustain the audience's attention for more than two and a half hours. And, perhaps surprisingly, Downe just about pulls it off.
There were some iffy moments in Downe's Million Sellers show on Sunday night. The temptation with this sort of act is always to flog the horse well beyond rigor mortis. Did we really require an interminable spoof spy sketch featuring a cod Polish singer, Dusky Vespa? And the idea of Dusky's cousin, the Brazilian support act Pastel, doing Eurovision versions of indie chart hits was distinctly overplayed. By the time we had reached the Europop interpretation of "Hit Me With Your Rhythm Stick", we really had got the idea.
But the sheer panache with which Downe performs his naff act carries you along. Anyone who can get a whooping round of applause each time he reappears in an increasingly nasty safari suit clearly has the audience onside.
From the too-white teeth down to the too-short trousers, Downe certainly has the light entertainment accoutrements to a T. For any comic performer, the devil is in the detail. He subtly rearranges his trousers before trying to hit the top notes, and he boasts a sculpted blond barnet which he scrupulously protects from naked flames.
As played by Australian performer Mark Trevorrow, Downe taps into the current vogue for character comedy, and he's at his most playful when pointing up the gap between act and actor. Coming on at one point in an unbelievably tasteless outfit comprising a stripy blue-and-cream golfing jumper tucked into brushed denim jeans, he observes that: "When you look good, you feel good about yourself. So by rights, I should top myself about now."
Downe embodies all those late 1990s buzz-words: camp, kitsch, tacky, cheesy. A self-conscious tribute to showbiz vacuity, he delivers the perfect post-modern show - ironic Easy Listenin'. Put another way, his whole act is a tale told by an idiot, full of sound and fury, signifying nothing.
Bob Downe plays Croydon Ashcroft Theatre tonight (0181-688 9291). Then touring nationally to the end of April, including 13, 14 and 15 at the Bloomsbury Theatre, London (booking: 0171-388 8822)