Martin makes sure Private Lives has a public meaning

During his time as co-artistic director of Chichester Festival Theatre between 2002 and 2005, Duncan directed the likes of Gilbert and Sullivan's The Gondoliers and Cole Porter's Out Of This World, and won a Best Musical award for How To Succeed In Business Without Really Trying. Duncan also directed Sondheim At 80 for the BBC Proms, as well as touring his production of The Rocky Horror Show to Munich and Milan.

Alongside work on numerous operas across the globe, Duncan directed and co-wrote Matthew Bourne's The Nutcracker for Opera North at the Edinburgh International Festival. In even poppier terrain, Duncan was an associate director on Performance, the 1991 tour by that most archly theatrical of bands, Pet Shop Boys. As a composer himself, Duncan has written for theatres such as the Royal Court and the Citizens, and has written libretti for two short operas. Duncan has also sustained a long musical partnership with actor Brian Protheroe, who had a 1974 chart hit with Pinball, in which Duncan makes a lyrical cameo.

Duncan is no gadabout, however, and beyond his musical adventures has directed plays by Gogol, Brecht and Beckett during his time running Nottingham Playhouse in the 1990s. Having also appeared in several of Coward's plays while still an actor, Duncan understands the light and shade of their author more than most. Indeed, for all Coward's perceived frothiness, it is somewhat surprising to hear Duncan make parallels between Private Lives and another classic play an altogether different reputation.

"It's like Waiting For Godot," Duncan says of the similarities between Coward's play and Samuel Beckett's era-defining piece of existential vaudeville. "Someone said it is like theatre of the absurd, because nothing happens. It's just people talking. Of course, people come together, people split up and there is a big fight scene, but it is just a lot of talk. I have never compared Coward to Beckett before, but Private Lives really is an absurdist play that exists in the limbo of this little cosseted world, and people talk. Most of Coward's plays are about relationships, and are about banter and chat and analysing things, but the words are very good."

Private Lives focuses on Elyot and Amanda, a divorced couple who, while on honeymoon with their new spouses, Sybil and Victor, discover they are in adjacent hotel rooms. There is clearly some unfinished business between Elyot and Amanda, who, despite the hostilities that ensue, rediscover genuine affection for each other between the acerbic barbs they exchange.

Coward wrote Private Lives when he was 30, and in the play's original production played Elyot himself, opposite Gertrude Lawrence as Amanda, while a young Laurence Olivier played Victor. The production opened in Edinburgh, at the King's Theatre, before embarking on a national tour prior to transferring to the Phoenix Theatre, London.

Where many productions of Private Lives have seen Elyot and Amanda played by more senior performers, in terms of casting, Duncan has looked to Coward's own youth when he originally appeared in the play to give it a sharper and sexier appeal.

"I have seen older actors doing it," Duncan says, "and you think, 'Well, aren't they old enough to know better about these relationships they are careering in and out of?' Whereas when they are 30 it makes so much more sense. They are still full of life and fun, and they are still sexy, and it is suddenly much more exciting having these two sexy, vibrant people rather than someone who's over the hill."

As an actor for 25 years, Duncan appeared in one of Coward's Tonight At 8.30 plays, in which he also played the piano. He has also appeared in productions of Hay Fever, played egomaniacal actor Garry Essendine in Present Laughter. Duncan also wrote songs for a play called Cowardice, which starred Ian McKellan, Janet Suzman and Nigel Davenport in a piece about a brother and sister who made-believe they were Coward and Lawrence. Duncan penned a pastiche of a Coward song for McKellan to sing.

"I have always been a fan of Coward's," Duncan says, "and have a history with his work, but until now I have never directed any of his plays. Since leaving Chichester I have directed only operas, so this is the first actual play I have directed for seven years. People said to me when I was younger that I would be a natural to do Coward parts, and I don't know whether that was the case, but I seem to have done quite a lot of them.

"I was telling the guys in Private Lives about when I was doing Garry Essendine, and how, night after night, it was like doing a steeplechase. You would see the hurdle coming towards you, and you knew that if you leap at the right time, you will get over it and get a big laugh, but if you just stumble and make a glitch, then you won't. It is a technique. Delivering Coward's lines is a technical thing, and yet they have got to look spontaneous. You have to not make it so flippant that you are not interested in or believe in the character."

This sense of truth goes some way to explaining Coward's enduring appeal.

"People are looking for something funny," says Duncan, "but they also want something that is clever, and so much of what passes for comedy these days is not clever. People say Private Lives is a frothy play, but it speaks an awful lot of truth about relationships.

"I am certainly not doing a dark version, but there are these little moments of introspection. It is not just about fun and froth. There is a sadness and a lost feeling that is about people struggling to find both themselves and each other.

"That is why Coward's plays have survived. If they were just about froth without the truth, they would have disappeared years ago."

Private Lives is at Royal Lyceum Theatre, Edinburgh, from February 14 to March 8

l www.lyceum.org.uk