Mr Dyke played the old DG in the mystery, that is "door guy"

The murder mystery play, broadcast on Wednesday on radio and on the BBC Devon website, was set at Burgh Island Hotel in south Devon in 1952.

Listeners joined in to identify the murderer of a wealthy film star played by television presenter Judi Spiers.

Money raised by listeners will go to the BBC Radio Devon Chestnut Appeal.

Murderous acting

Judi Spiers played actress, writer and publisher Melanie Martin.

After she was killed, it was up to Det Insp Roy Longbrook, played by Edmonds, to carry out the unenviable task of working his way through all the motives of a cast played by staff at Radio Devon, including station managing editor Robert Wallace.

Noel Edmonds said: "Longbrook is marginally incompetent and overawed by this, which is his first murder case.

"In fact, you could say my acting murdered the whole thing.

"I'd never done anything like this before, but I leapt at it. And it got a good end result because we raised money for a good charity."

Noel Edmonds gets into his 1952 character in sepia tone

Edmonds added that he thought the idea of getting listeners to join in as detectives was not only a rare thing for a local radio station, but even for a national broadcaster.

He said: "We've looked into this and we can't find any other broadcaster who's done anything quite like this before."

Greg Dyke made a cameo appearance as a member of staff at the hotel where the murder took place.

During the play, upon seeing Spiers' character, he said: "'Ello, love. I'm your old DG. You know, door guy.

"Blimey, a WMD, a woman of mass distraction. I'd better send a 45-minute warning to the staff."

Money raised by about 1,300 listeners who applied for a detection pack to join in the mystery will go to BBC Radio Devon's Chestnut appeal, which is raising cash for a prostate cancer unit at Derriford Hospital in Plymouth.

Mr Dyke was in charge of the BBC from 2000 until January this year.

He was forced to resign after the Hutton report concluded the BBC had been wrong to claim the government "sexed up" the Iraq weapons dossier.

And if anyone wants to find out whodunnit, the play is available in an on-demand stream at the BBC Devon website.