David Hare’s play Plenty, about ideals and disillusion, went out yesterday on Radio 4 — in the wake of the Labour party conference, aptly. Occupying the same slot this week is Robert Bolt’s A Man for All Seasons.Next week, we have the long-awaited sequel to Peter Pan, commissioned by Great Ormond Street, which is so hush-hush I am being allowed a preview copy only after signing a confidentiality agreement. Tom Stoppard’s infidelity drama, The Real Thing, will also be heard before Christmas: Trevor Nunn, who directed it at the National, is likely to do so again.

These are all big, splashy, Saturday-afternoon productions, but the most significant thing is that they last 90 minutes. This has been an endangered species at Radio 4 for the best part of a decade, with only two or three a year — an occasional Agatha Christie, perhaps, or an E Nesbit on holiday weekends, when children are listening. This year, however, there will be no fewer than 16, plus one (Arthur Miller’s Death of a Salesman, starring Timothy West) lasting two hours.

It is an extraordinary expansion. The playwrights have included John Osborne, Caryl Churchill, Alan Bennett and Hugh Whitemore, and the casts Miranda Richardson, Michael York and Hollywood’s Teri Garr.

Some of the plays were new productions of Royal Court successes, to mark its 50th birthday. Others have extended the life of West End hits, such as Joanna Murray-Smith’s Honour, with Diana Rigg, and Simon Gray’s Quartermaine’s Terms, with Michael Palin. The current mini-season, whose theme is betrayal, also revives celebrated works for the stage.

Those listeners who have campaigned for the return of 90-minute plays, by writing to Feedback or protesting on message boards, will feel vindicated. But Jeremy Howe, who commissions drama on Radio 4, points out that the network’s controller, Mark Damazer, publicly promised to beef up drama when he got the job. “He felt there had been this starburst of theatre writing over the past 50 years, which Radio 4 hadn’t reflected.

"We don’t know whether the 90-minute plays have gained bigger or smaller audiences than our 60-minute ones, and we have commissioned some research on listeners’ reactions. Anecdotally, we feel people have enjoyed them. The production that created the most waves this year, which was shortly after I arrived, so I can claim no credit for it, was Death of a Salesman. That was both the longest and a repeat. There will be another season of stage plays next year, too. Mark is keen to get the different drama strands clearly differentiated.”

As nearly all these long dramas are radio versions of stage plays, there is always a danger of original dramatists feeling they are excluded (although the 90-minute play has also been kept alive both on BBC7 and Radio 3, which tonight mounts a new Howard Barker play of that length set in 5th-century Rome). In addition, the fact that something is 90 minutes long is not in itself a guarantee of quality. But one outing for a play on Radio 4 gets a bigger audience than a six-month run in the theatre, so is not to be sneezed at. And a 90-minute play can be a wonderful thing to settle down with, just as a novel is more satisfying than a novella. Length isn’t everything, though sometimes it helps.

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