'Real Thing' not real; 'Measure' too light; 'Bishop' won't fly; 'Messiah'

Imagine a roomful of Tom Stoppard's characters in ''The Real Thing'' talking privately after a performance: ''All right,'' one would say, ''we're all very British, we're all very funny, but who are we?''

''Well,'' answers Henry (Jeremy Irons), ''I'm a playwright. I like Neil Sedaka and Buddy Holly. On the surface I'm very flip and careless, but underneath I'm caring and monogamous.''

Not good enough, Henry. What's really going on with you? What happens when the one-liners stop and the silence begins? What is in your heart of hearts?

There would, of course, be no answer, because, strictly speaking, Stoppard does not create characters, he makes vehicles. The play is not the thing, nor are those who people the play. ''The Real Thing,'' like everything else I've seen by Stoppard, is a vehicle for his enormous wit.

And wit there is. Machine-gun wit that keeps almost everybody laughing. But, just once, you'd like to see a character buckle, lose his cool, and remain believable. And that just doesn't happen.

''Are you there, Henry?'' one character demands; ''say something witty,'' as if to underscore the fact that the only way these characters can prove their existence is to be terribly British and funny.

Not that there aren't delicious theatrical moments to be found on this revolving stage that turns like a giant Lazy Susan, giving us prismatic glimpses of the same infidelity refracted in artificial and so-called real life. Jeremy Irons is capable of the kind of aplomb called for here. Glenn Close, lovely and lithe, tests our capacity for half-closed eyes and half-uttered silence.

Max (Kenneth Welsh) spells out the real problem with ''The Real Thing'' when he turns and tells Henry, ''There's something wrong with you. Something missing. You may have all the words. But having all the words is not what life is all about.''