IT'S VERY EASY to get sidetracked by a show like Elvis on stage. The simple line is to speculate on why people should be expected to flock to see a montage of Presley facsimiles act out the various stages of his career. The simple question are who needs it, is it a celebration, a tribute or a cheap cash in?

The answers are pretty simple, too. Obviously someone - presumably producer Jack Good - decided the original Elvis charisma was sufficiently powerful to attract a viable audience to third or fourth hand imitations of the real thing.

Jack Good does, after all, have the surface credentials to carry off this kind of project. Didn't he produce Six Five Special, Oh Boy, Shindig and the first Beatles TV spectacular?
Wasn't he also the man who brought Gene Vincent to Britain, dressed him in black leather and gave the divine bopper a whole new lease of life?
Surely if anybody could stage a musical biography of Elvis Presley, it had to be Jack Good.

And indeed, he has done something of the sort. There's certainly a Elvis musical at London's New Astoria Theatre.

As a fun night out for mum, dad and the kids, it's harmless enough. There's a lot of songs, 82 of them in all (some are just fragments, of course), most recorded by Presley plus a few inserts like "I Want To Hold Your Hand" and "Goodnight Irene" which point out the march of time. There's energy, a few laughs, a good deal of broad, easy to understand irony and the obligatory tear jerk by way of conclusion.

What isn't immediately clear is the point of entire exercise.

The story is simple. It adheres strictly to the non-controversial canon of the Elvis legend. Dialogue is dispensed with. The narrative is carried by broad (or crude) back-project photos and films that are flashed up giant screens that box in the stage.

The opening is quite intriguing: the final few minutes of a Marx Brothers movie (Love Happy, to be precise). This is followed by an advert for ice cream and candy, informing us that we're in Loew's cinema in Memphis. The year is 1951. After two singing cowboys work out on a tune, the "singing usher", 16-year-old Elvis Presley, is brought on stage from the audience to perform a sincere, if, nervous, rendition of "Old Shep".

So far, so cute.

Unfortunately the charm quickly wears thin from then on. Taking the production as a whole, the kindest thing you can say about it is that it's patchy. Jack Good's heritage streams from every pore in the show. The overall effect is something akin to a tribute to Elvis on the Donny and Marie, except that some slabs of social realism, back flashes of depression ravaged share croppers. Billy Graham, Hitler, Russian tanks in Budapest, are inserted in a play for significance.

After a nationwide search Good found himself three individuals to portray Presley at the different stages of his life. The youngest is a unknown 16-year-old schoolboy, Tim Whitnall. Whitnall is good-looking, has a potentially fine voice general boasts all the ingredients in flutter teen hearts that already held in thrall Messrs Rotten, Strummer or Idol. Given the right career opportunities he could quite easily piss all over David Essex.

As Pressley, however, he only rates a brave try. This is hardly his fault. He's Obviously too young to have any direct experience of Presley in the first youthful flight. The blame has to rest on the choreographer. (credited as Carole Todd), who has totally failed to teach him the basic mechanics of Presley's movements. He tends to flounder when he should be fluid and pose when he should be passionate.

Shakin' Stevens acquits himself far more creditably as the middle Presley. He carries the weight of the rock and roll material and obviously cares deeply about what he's doing. Stevens is, after all, a well respected jobbing rocker (and so, for that matter, was Elvis Presley), albeit on a much more elevated level. He has clearly studied Presley's moves probably most of his life, and although he doesn't have the agility or build to duplicate Presley's wilder displays, he knows his limitations and works well within them.

His voice is powerful and experienced, and he seems to be sincerely trying work into the part, and not just run through an Elvisised version of his own stage routine.

Unfortunately the same can't be said for P.J. Proby, although he bears a passing resemblance to the late period Presley, he appears to be totally engaged in remaining Jim Proby. His suits are well made. His voice is strong enough to carry Elvis's Vegas ballads, and that appears to be enough for him. When he goes into one of Presley's often-filmed routines it's lax, perfunctory and occasionally grotesque.

He even slips in a few of his own `60s trademark mannerisms, almost as though he had decided that his schtick was superior to Presley's.

Okay, so Proby may consider himself to be some sort of rock and roll legend, but he is supposed to be playing Elvis Presley and if he tried as hard as Shakin' Stevens he might have pulled of a coup. As it is he just seems to pose his way through the entire part. When he gets to the "American Trilogy" finale, it's obviously supposed to produce a mighty run of Kleenex. In fact, he manages to reduce the sequence that segues from "Dixie" to "Battle Hymn Of The Republic" to "All My Sorrows" in depressing kitsch.

Apart from Shakin' Stevens, the hardest working people in the show are the augmented Fumble, who are onstage for the whole two or so hours and lay down the backing like the road hardened professionals they undoubtedly are.

Over the past ten years there has an awful lot of glib talk about so-called rock musicals. From Hair to Rock Follies, too many people have assumed that his is a kind of happy marriage between rock and legitimate theatre. Following on from this premise we've had the age of Bloody Aquarius rammed down our throats until I, for one, feel physically ill.

The truth is rock musicals precious little to do with rock and roll.

With exception of a few serious non-rock composers like Stephen Sondheim, the musical is a vehicle for escape. It's no coincidence that World War II was a prime era for lavish shows. The musical is a excursion into cloud cuckoo land, a place where boy meets girl (or God in a few recent cases) after a few trivial tribulations lives happily ever after.

On the other hand, the majority of rock and roll that's worth its name has some sort of connection with reality, however tenuous.

Elvis On Stage does manage to avoid one of the worst pitfalls. There are no specially written show tunes. Every not comes from Presley's repertoire.

It does, though, fall squarely into the other trap. It attempts to formularise the story of Presley into a jolly singalong with some vague look-alikes and leave the audience with a weep at the end.

You simply can't do this to the Elvis Presley story. A musical requires the suspension of belief; rock and roll requires empathy.

The two do not mix.