Long John Silver, the piratical villain of Treasure Island, was a fictional character based by Robert Louis Stevenson on his one-legged literary sidekick in Edinburgh, William Henley. For his enthralling new play, the first presented in Dominic Dromgoole’s regime at the Globe, Simon Bent has imagined an early life for Silver, long before he led his motley crew of buccaneers on the Hispaniola in search of Captain Flint’s booty.

So, there are no cries of “Jim, lad” or squawks from a parrot or even choruses of “Yo-ho-ho and a bottle of rum.” There are, however, a series of fairly rousing choruses composed by Orlando Gough, the first of which welcomes the joyful day of King Charles I’s execution – the first scene of the play – with a cry of “freedom”… and more beer. There follows an exhortation by Silver’s father Ebenezer (Howard Ward) to remove trousers, which he promptly does, to the audience’s delight.

The outline of Bent’s play, which stretches over five boisterous acts and is directed with considerable brio and panache by Roxana Silbert, follows Silver’s disillusion with the new protectorate of Oliver Cromwell, his decision to abandon his wife and child, his encounters on the high seas with rival pirates, notably the swaggering Dutchman Kees de Keyser (Nicholas Tennant) known as “the king of the Barbary coast”, his conversion to Islam while insinuating himself with the Sultan of Morocco (Joseph Marcell), and the details of how he came by his soubriquet (“Is it short, or is it long?” is the gist of an intimate locker room enquiry) and lost his leg in a battle.

In truth, it's actually quite hard to follow exactly what's going on as the action sprawls across the ocean and the pirates create their own spurious form of waterlogged democracy as an antidote to the political injustices at home. An informative programme note fills in the background on the 17th-century piratical parliament of Bou Regreg based on the Atlantic coast of Morocco. Here, we even find a chap called Hamlet (Mo Sesay) who is branded in the eyes and disposed of in a hessian body bag.

The fine Scottish actor Cal MacAninch as Silver is projected through the middle of these escapades en route to emerging, more or less, as a fully paid-up terrorist. His raggle-taggle army includes names later familiar to us in Treasure Island: One-Eye Pew, Black Jack and little Ben Gunn (Paul Hunter), not yet the mad recluse of Stevenson’s novel. MacAninch, lean, mean and hollow-eyed, cuts a charismatic figure in a company that seems to have come alive in the demands of the play.

For although Bent conceived of his story as a film script, there's no doubt that the writing rises to the challenge of the theatre, and its “out on a spree”-minded audience - proof (if any was still needed) that the size of the tiny Bush theatre, which Dromgoole ran for many years, diminishes the scale and ambition of dramatic writing, however quirky or incendiary it may be, and has stunted the growth of countless playwrights.

- Michael Coveney