What he did not realise was that by then, 50 years of comic acting tradition would have intervened to cloud the crisp clarity of his work. Gareth Armstrong's production of Blithe Spirit is a mishmash of styles, from the heightened outrage of Ayckbourn to the cartoon caricature of 'Allo, 'Allo. There is still a masterpiece underneath, but attempts to tart it up serve only to detract - as if someone has pebbledashed Rouen Cathedral.
The fault lies primarily in an apparent lack of faith. There seems to be an overwhelming devotion to getting the laugh from the portrayal - the funny walk or the comic grimace - not the line. Many of the cast stretch themselves to drag a giggle where no giggle should be dragged, all too often at the expense of Coward's expertly crafted writing, with - paradoxically - many comic throwaways simply thrown away.
The greatest harm is done by Fenella Fielding's Madame Arcati. Her drawling eccentricity and grinding comic "business" do the script no favours at all, ruining the pacing and rhythm of Coward's wit.
But the production is saved by Celia Nelson's Ruth. In a play about reincarnation, it is spooky to see an actress who is such a complete embodiment of a young Glenda Jackson. She plays the aggrieved second wife, displaced by her predecessor's ghost, with scalpel precision - and she justifiably garners most of the laughs. As her deceased rival, Mairead Carty makes an excellent Puck. However, when she forgets this she becomes a fine, petulant Elvira.
Ultimate responsibility must be laid at the door of the director. Gareth Armstrong seems to have devoted too much time to blocking the characters in a whirlwind of moves so convoluted as to induce dizziness, and too little time to ensuring that the cast grasped the art of Cowardian comedy, a skill as specific as commedia dell'arte or Noh theatre.
You have to strip away a lot of the staging to get to it, but Coward's script still shines through, the lines and laughs as pure and entertaining as they were when he wrote it - in less than a week - 58 years ago.
The production amuses, but despite the contemporary "improvements", not because of them. We can still agree with Coward's modest assessment, "with the maximum of self-satisfaction, that those six days in Portmeirion in May 1941 were not wasted". It will take a different production, however, before Blithe Spirit's true qualities are once again fully displayed.
Booking to 13 Feb (01722 320333)