The occasion is an auspicious one. To celebrate his 80th birthday, Sir Peter Hall - founding artistic director of the Royal Shakespeare Company; former artistic director of the National and the man who introduced Beckett's Godot to the English stage - returns to the National with Shakespeare's delicious comedy.
To further whet the appetite, the strong cast boasts the director's daughter and fast-rising film star Rebecca Hall in the role of Viola, and the lip-smacking prospect of Simon Callow as the drunken Sir Toby Belch.
Hall's hallmarks of clarity and simplicity are obvious from the off. The first impression is of a classic washed in spring water. The dress is Elizabethan and Anthony Ward's unfussy design primarily consists of bare boards and an elegant awning under which Marton Csokas's decadent Orsino lolls on cushions, and which, when lowered, forms the beach on to which Hall's glistening Viola has been washed up.
The transition is exquisite. And with the entrance of David Ryall's world- weary Feste - an aging Fool who is in constant fear of losing the wit that sustains him - there seems every chance that this Twelfth Night will match even Sam Mendes's final Donmar production that starred Simon Russell Beale as Malvolio.
But that hope first begins to evaporate with the credibility gap that appears between Hall's Viola and Csokas's Orsino, the man who Viola is supposed to fall instantly in love with, but who, in Hall's version, falls into something like indifference with. Who can blame her? Exactly what quality is she supposed to have fallen for with this moping Orsino? The yearning that lies in this melancholy lion's loins comes across as something more lascivious than love; something more pervy than passion.
Just as crucially, the moments that promise comic ecstasy are less than hilarious. Perhaps Hall (the director) was looking for something more modulated, a kind of comedy that is more nuanced than broad. Yet the result is that the agonising pleasures of this play are often muted. Even the humiliating transformation of Simon Paisley Day's funereal Malvolio into a yellow-stockinged buffoon comes across as surprisingly underpowered.
And although the comic double act of Callow's blood vessel-bursting Belch and Charles Edwards's endearingly stupid fop Aguecheek bears glorious fruit - especially in the garden scene - we and the production miss their energy when they leave the stage.
But there is still a great deal to enjoy here. There is - not least of all Amanda Drew's intelligent Olivia; probably most of all David Ryall's truly great Feste - the best I have seen. And then there is Hall, the younger, who understandably unable to throw herself body and soul into the role of a woman in love, delivers a now oddly motivated Viola with a cool understatement that is interestingly subversive, if ultimately out of place.
This play, with this cast and most crucially of all, with this genuinely great director, was always in danger of falling short of expectations. With one or two different casting decisions, the result might have been the hoped-for definitive version of a classic. Instead, a good production amounts to less than the sum of its many terrific parts.