The Winslow Boy Production Images
Naomi Frederick & Henry Goodman in The Winslow Boy

Even in a decent, unevenly cast production such as this Old Vic revival by Lindsay Posner - Peter McKintosh's design is nothing special, Tim Mitchell's lighting over-shadowy - Rattigan's 1945 play about the Edwardian middle-class young boy alleged to have stolen a five bob postal order is confirmed as a modern classic.

The House of Commons gets in a tizzy over the family's petition of right to a trial (at first blocked by the Admiralty, which has "sacked" the boy from the naval college at Osborne) and is described as a place of too little ventilation and too much hot air; the last revival I saw, Stephen Unwin's for the Rose in Kingston, coincided with the climate of outrage over MPs' expenses.

The focus shifts this time, as our Parliament dithers over the recommendations of the Leveson Enquiry, to the media frenzy surrounding the case, the flippantly intrusive interview of a "lady journalist" (a vividly insensitive Sia Berkeley) and the price the family pays for justice.

A grumbling, grumpy Henry Goodman is not ideally suited to the role of Arthur Winslow, the retired banker with a stiff upper lip and a forbidding exterior, but he fully conveys the physical toll the case takes, his wincing arthritic movement apparently a symptom of a deep spiritual exasperation. Deborah Findlay as his wife converts her own sense of unease and foreboding into a slightly forced show of flippancy and idle chatter.

Ronnie, the Winslow boy, is a gangly, awkward but curiously mature-looking 14-year-old in Charlie Rowe's performance, and seems at first older than his senior sibling, Nick Hendrix's Oxford undergraduate wastrel Dickie; and he's too tall even to curl up asleep on the sofa as the argument rages around his head in the third act.

This follows the great second act show-down when Ronnie is interrogated by the star barrister of the day, Sir Robert Morton, with a view to accepting the brief. Instead of laying a silken trap for the boy with the usual controlled cunning, Peter Sullivan's Sir Robert initiates a shouting match; this is a bar-room brawl, not a drawing-room demolition, and it lowers the tone instead of intensifying it.

The great curtain-line still packs its punch, though, and Sullivan is suitably slippery (though too garbled on occasion); but what a role this might have been for Kevin Spacey! Sir Robert's chief adversary is Ronnie's suffragist sister, Catherine, here given the evening's outstanding performance by Naomi Frederick, superbly chiselled and articulate, but willowy, sensuous and briskly intelligent, too, a model New Woman and conscience of the play.

Rattigan's perfectly crafted drama deploys information and narrative over two years while charting upheaval and change in all the characters' lives: the financial costs, and the notoriety of the case, affect Dickie's career - he leaves Oxford and buckles down as a banker ("You can't keep late hours in Reading") - and Catherine's private life (her fiancé, nicely done by Richard Teverson, is the disapproving scion of a military family).

Ironically, Ronnie himself is happily accommodated at a new school, which raises the further question: is all of this worth going through? Rattigan's play, set on the brink of a world war and first performed at the end of another, embodies a great truth about human rights and democracy by insisting that no cause is too trivial, ever, and that justice is merely the secondary, executive companion of fairness.