Longitude, Greenwich Theatre, London

The clockmaker as choirmaster

Harrison spent only a few early years in Yorkshire (he was born in Foulby, near Pontefract, and soon moved with his family to Lincolnshire), but he retained enough native obstinacy and outspokenness to make his derivation clear.

Arnold Wesker's new play, based on Dava Sobel's unlikely 1995 bestseller, Longitude, is a slighter version in some respects of Brecht's Galileo, showing in Anthony O'Donnell's performance a doughty little curmudgeon whose autodidacticism and self-belief carry echoes of Wesker himself.

A century before Harrison, the real-life Galileo's theories about the solar system were denounced as heretical, and Brecht's play shows an unscrupulous hedonist waving his telescope defiantly against the priests and philosophers at the Medici court.

Wesker's Harrison is similarly afflicted by "the priests and professors" ranged against him on the Board of Longitude. They continually denied him the government's prize of £20,000 even though he had invented a reliable sea-going clock to read longitude and thus ensured the future of the nation's naval expeditions, and indeed of its imperial domination. The Establishment was more interested in the lunar distance techniques nurtured at the Royal Observatory, founded by Charles II in 1675.

And besides, Harrison was an upstart, a "not one of us" kind of figure. In Charles Sturridge's 1999 Channel 4 film, Michael Gambon exuded much more technical nous and passion than does O'Donnell. But this fine little character actor is given another string to his bow in the revelation that Harrison was also a choirmaster and bell-ringer.

So, Fiona Laird's lucid and enjoyable production, set on a raised disc like a clock face, is flecked with anthems, shanties and old folk-songs intoned by a chorus of dead sailors who double as the obstreperous board members. Harrison's mission is fuelled by these memorials to lost lives and cargo. Finding latitude at sea was a doddle. Longitude was the problem, and it needed solving.

The brilliance of Sobel's book is that Harrison's campaign is part of a much bigger story and, in concentrating on the personality clash at its heart, Wesker reduces the significance of what is happening. There is also a deadly repetitiveness about O'Donnell's bull-like charging into the wall of indifference.

Eventually, George III (wittily done by Dominic Marsh) intervenes personally to see Harrison home, aided by the support he receives from his long-suffering wife (Mossie Smith) and clever young son (Hadley Fraser).

Given that you can visit the Royal Observatory and see Harrison clocks and chronometers in the nearby National Maritime Museum, the show seems to have missed a trick or two in not injecting rather more local flavour.

But the subject is so interesting - and an audience can always pick its way round the subject at a play like this - that one is glad to have seen it at all. Good news, too, that Greenwich shows signs of producing its own work again after so long a period as a clearing house for small-scale tours.

To 29 October (020-8858 7755)