Geoffrey McGivern and Simon Jones voice Ford Prefect and Arthur Dent

The last instalment of the series, based on author Douglas Adams' final two books, will feature Stephen Fry, Jackie Mason and Jonathan Pryce.

Sandra Dickinson and Bill Paterson - who appeared in earlier adaptations of the stories - are making a return.

An unnamed "Hollywood heart-throb" is also set to join the cast during the final radio series, beginning on 3 May.

Hollywood version

Actors from the original 1978 radio series, Simon Jones and Mark Wing-Davey, are among the surviving cast members who are returning for the final instalment.

Sandra Dickinson, who played Trillian in the BBC television adaptation of Hitchhiker's in the early 1980s, will play Tricia MacMillan, along with David Dixon, who was Ford Prefect in the small screen version.

Stephen Fry, who is playing Murray Bost Henson in the forthcoming radio series, is the Voice of the Book in a forthcoming Hollywood film version of the story.

Sandra Dickinson, Trillian in the TV series, is also in the radio finale

John Malkovich, Bill Nighy and Alan Rickman also appear in the big screen adaptation, released in UK cinemas on 28 April.

The BBC website connected to the Hitchhiker's Guide - h2g2 - is being updated to coincide with the drama's final radio outing.

Some of the entries in the guide which can be called up on PDA include how to hypnotise a chicken and an 18-part entry on the historical references in Billy Joel's We Didn't Start The Fire.

Internet repeats of Hitchhiker's recent radio outing last autumn drew up to one million listeners.