The problem with national treasures is that they can start to give off the whiff of the museum. So it proves here, as Edward Fox throws himself with crusty gusto into a pair of John Mortimer legal comedies that have not aged well.

The Dock Brief and Edwin are elegant, witty works but so laboriously pleased with themselves and their observations on the stagy nature of the law that they put under severe strain the innate affection one feels for both writer and actor.

Admittedly, I went to see Christopher Morahan's production two days before opening night, but its deficiencies are down to content and style rather than lack of preparedness.

Both plays started out on radio, and it shows. In the Dock Brief, from 1957, Fox is a lordly but hopeless barrister drawing his overawed, working-class client (Nicholas Woodeson) into a fantasy world of courtroom theatrics where a murdered wife and a possible death sentence scarcely matter.

In the even more static and wordy Edwin, from 1982, he is a retired judge amusing himself in his garden by constructing elaborate legal arguments concerning his wife's supposed affair with a neighbour, and the parentage of his son.

Both are plays that draw thin, blithe humour from actually rather awful situations. The assumptions about class in the first play are almost as discomfiting today as the assumptions about women in the second.

Then there's Fox. While Woodeson casually displays his versatility in two very different roles, Fox is all magnificent mannerism.

His voice seems to have atrophied into a parody of upper-class enunciation, half-clipped, half-drawl. His body language, too, from arched eyebrows to stiffly wagging fingers, has become a masterclass in condescension. He goes at his own slow, sweet pace.

If Disneyland wanted to construct an animatronic figure of a wry, wise old bird, they should study Fox. Technically, this is a brilliant performance; but it's a star turn that constantly draws attention to itself.

Maybe this is all audiences want from Fox and from Mortimer. For my own part, m'lud, I'd like a slightly fresher pair of briefs.

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