The Story of the Guitar, BBC1, 10.50pm The South Bank Show, ITV1, 10pm

Beginning his three-part Story of the Guitar , self-confessed middle-aged wannabe rock'n'roll axe-hero Alan Yentob trailed a compelling lure before us other Johnny Never-Was six-string-razor kings. Very blokey TV, this was.

The show's opening 10 minutes snared us with choice vintage clips capturing how life in dull post-war Britain erupted from monochrome to full colour between the years 1956 and 1964 thanks to deft bursts of fizzing, electric git-box blare. Greased and throbbing, young Elvis thrusted his pelvis into his Martin D-28; Pete Townshend windmilled his arm and cranked out angry clangour on his Rickenbacker.

More enticingly, The Story of the Guitar held out the shockingly poetic promise of unfettered fretboard raunch via a frank utterance from guitardom's most prosaic and least raunchy man. I am referring to he whose best-selling manual assured every impatient 10-thumbed clod he could play the guitar in a day: Bert Weedon!

A very old, time-crumpled figure these days, the never-cool Bert belied his grandad looks in hymning the guitar's primal form with a hot simile.

"It's a sexual, beautiful thing," Bert purred. "It's like a beautiful woman, you can cuddle it." Jings, the old boy's still got it like he surely never had it before!

Sadly, sexy and cuddlesome beauty was in short supply thereafter as Yentob's show chose dusty historical and academic mode, despite the fact that the guitar - with its swelling hour-glass figure - has always played a seductive role in male-female relations.

And so the lyre first emerged as an acoustic instrument of desire, as Apollo pursued the nymph Daphne. The lyre begat the giterne, which lay with mediaeval slatterns, and evolved into the sixteenth-century cittern, facilitating nocturnal serenades of balconied babes by strolling players.

From here, Yentob strode on with sudden swiftness to the Mississippi delta, pausing not to listen to the rumbling blues but to watch men slowly, oh so slowly whittling $325,000 bluegrass guitars from Brazilian rosewood.

Singing cowboy Gene Autry sang not very well to his horse; Bert Weedon remembered Django Rheinhardt not very clearly. There weren't enough simple and rambunctious old rock film clips, which was annoying given that The Story of the Guitar had begun by quoting the studied dumbness of sauce-master Keith Richards: "That little round hole and that bit of wood, that's the truth."

In truth, The Story of the Guitar took its low-slung subject to school when it should have been hanging out with it in low-life bars.

There was something likewise disappointing about The South Bank Show , in that it allowed its subject, Ronnie Corbett, to cloak his understated comedy genius in modest self-camouflaging ordinariness. And so it duly emerged that dapper Ronnie enjoys doing the ironing and washing his woollens, being keen on the long-life care of cashmere jumpers.

Every so often there was a glimpse of a long-lost showbiz era, as when Ronnie's wife, Anne, admitted that when the couple had first met, she'd been "married to a Jones Boy who became a Raindrop". As you'd imagine, it wasn't a happy experience.

Nowhere, however, was it sufficiently acknowledged that Ronnie Corbett is a master of comic timing with a unique insight into funny wordplay, good writing and making people laugh - or, as he summarised his old oppo, Ronnie Barker: "Sound taste, great craftsman." Tragic, that.