The saga of RSC's King Lear - Trevor Nunn directing, Ian McKellan starring - is well-known. Briefly, its press view, scheduled for April 3, was postponed because of injury to Frances Barber (playing Goneril), and ended up nearly eight weeks late, on May 31. Nunn has been much criticised for this decision (which is now revealed to have been made by artistic director Michael Boyd). But, apart from my feeling sympathy for Barber, knocked off her bike and hurting her knee (bad luck Frances, we've all been there) a major international tour hung on her availability for the central role of Arkadina in Chekhov's The Seagull. So we were the first to see the double-bill.

Ever thought of Lear as an epistolary play, as Liaisons Dangereuses is an epistolary novel? You'd be surprised how many letters are written, read, not read, delivered or torn up, as a glance at the props shelf reminded me. Actually Nunn starts with a blast on a mighty Wurlitzer as a procession of Lear's court lies prostrate at his feet - he clad in gilded headgear like a Doge or Oriental despot - before the opening dialogue.

Nunn is arguably the most experienced director around, bound to have ideas to contribute. He does - some good, some not. The love 'competition' is a sudden whim - the kingdom is already divided on the map - surprising everyone. Goneril and Regan take stance at the lectern, visibly summoning their hyperboles. The king's rage at Cordelia's failure amazes everyone, as he strikes Kent, then clutches his aged back in pain. Nunn humiliates Cordelia further by protracting her rejection by the Duke of Burgundy.

Lear's knights really are unruly, though they needn't be Cossack dancers. His Fool (Sylvester McCoy) puts over his barbed songs and bitter jests with great clarity, hiding under an absurd red wig the grey head that makes him the king's coeval. Edmund (Philip Winchester) is a personable villain, but why have Edgar (Ben Meyjes) a bespectacled bookish nerd unlikely to become a military champion and inheritor of the kingdom?

Jonathan Hyde is a dignified, nobly-spoken Kent, but it's plain crass to have him rush off after giving the most beautiful couplet in the play, pistol in hand, to suicide. The time for action is past. The tableau of the dead king and his daughter should claim all attention, and the faithful thane should be there. The growing jealousy between the sisters is excellent, and Goneril's poisoning of Regan (Monica Dolan) neatly achieved by the doctor's medical box left on stage for her to pilfer. Julian Harries is unusually successful in charting Albany's growth from dullard to capable general. McKellan's king, frail but dangerously whimsical, grows in pity and understanding - his scenes with the other old men, Gloucester and Kent are touching, and his awakening to brief reunion with Cordelia moving.

And so to Chekhov - text by Nunn and company. The props shelf was full of luggage - carpet bags, battered suitcases - for the arrivals and departures of the cosmopolitan successful actress Arkadina and entourage at the country estate of her brother Sorin and his lovelorn household with hopelessly limited horizons.

There's birdsong and hammering as an amdram stage is prepared for Konstantin's (Richard Goulding, suitably chaotic) wordy Symbolist rant. The chain of unrequited passions is positively Racinian; the successful' actress and novelist Trigorin are selfish and insecure - those with unfulfilled ambitions have to stay that way.

Barber is a gorgeous bird of prey as Arkadina, very actressy in her tantrums; Guy Williams makes much of the estate manager with interminable unfunny anecdotes; Ben Meyjes scores again as the boring schoolmaster on whom sloshed snuff-taking Masha (Monica Dolan) throws away her life. Romola Garai's Nina seems too girly and light-voiced (as I also found her Cordelia).

McKellan touches in Sorin with real skill as l'homme qui a voulu' who never made it, though we'd hardly accept 62 as the end of life today. Jonathan Hyde again takes high honours as Dorn, one of those country doctors essential to a Chekhov play. To him falls the dreadful fact of Konstantin's suicide, as the cardplayers gather and Arkadina's unthinking laughter fills the fading stage.