CALL it synchronicity, if you like. On the very day that The Phantom of the Opera set the record for the longest run on Broadway, two young Americans were demonstrating just how much fun you can have driving a stake through the heart of a portentous, dumbed-down extravaganza.

Playing in a venue that is barely big enough to hold one of the Phantom’s famous chandeliers, Gutenberg! The Musical! — receiving its world premiere in London — contains more wit and intelligence than three decades of megashows.

Written and performed by Anthony King and Scott Brown, this small but perfectly formed entertainment embarks on a gleeful rampage through every stock device ever tossed in front of tour-bus audiences. If you want to bring a seminal historical figure to life, all you need are some illiterate medieval burghers, a handful of rock-lite riffs, some deliciously contrived anachronisms, a love interest called Helvetica and an ample supply of peaked caps.

Caps? Well, yes. With no scenery or costumes and only the pianist, Michael Roulston, for company, King (tall and preppy) and Brown (short and impish) signal changes of character by donning a selection of identical cruise-ship headwear emblazoned with the individual’s title. My favourite is the leering, bigoted flowerseller who runs amok under the label “Antisemite”.

Sometimes wearing a half-dozen hats all at once, the duo enact meticulously choreographed crowd scenes and deliver a string of dubious historical titbits.

The central conceit is that we are witnessing a run-through of a show that is desperately seeking a West End backer. Endlessly apologetic, the two performers supply a commentary on the nuts and bolts of modern musical theatre, introducing us to “charm songs” and all the other contrivances that are part of the composer and producer’s arsenal.

The evening could easily have slipped into cynical overkill, but the entire parody is delivered with the lightest of touches. Sometimes I found myself wondering whether the co-lyricists had been rummaging in Randy Newman’s desk. The satire is so droll, you could easily imagine it finding a place on one of his albums.

How did the rise of the printing press affect the Church? Why does the evil Monk speak in a Deep South drawl and why is he obsessed with sharpening pencils? Questions, questions. Gutenberg! delights in leaving them all hanging in the air. All that remains is whether the production can transfer to a larger space without destroying the chemistry. Fingers crossed.

Box office: 020-7287 2875 Theatre