Billy Connolly is to return to the BBC to star in his first radio drama as a modern-day Don Quixote.

The show, specially written for the actor and comedian, is to be broadcast on BBC Radio Scotland on Christmas Day. The actor and comedian has not made a show for the BBC since his last World Tour in 2004.

He will play the title role in The Quest of Donal Q, based on the windmill-tilting story of Cervantes’s famous knight of La Mancha.

In the play Donal is estranged from his brother Sandy, played by Hollywood star Brian Cox -- a friend of Connolly’s -- but Donal returns to Scotland to be a “knight in shining armour” for a woman friend in distress, and asks Sandy for help.

The play, written by David Ashton, represents the Scottish station’s biggest investment in radio drama for years.

Bruce Young, editor of Radio Drama at BBC Scotland, said the idea for the play began when Cox grew long hair and a beard for a movie role.

Ashton and Cox, who are also friends, joked that Cox could be Connolly’s brother. Cox then challenged Ashton to write a play which would star both of them.

Connolly agreed to be in the play last week and it will be recorded later this month in London.

In the play the two brothers have been separated since growing up in an orphanage.

Connolly’s Donal has had a successful life in the US, while Sandy has had a less glamorous life in Dundee running a tobacconist’s shop.

Mr Young said one of the pair is a bit more practical than the other, in a way similar to the divide between bumbling Don Quixote and Sancho Panza in the Cervantes novel.

“It’s very funny, but David is a very funny writer: he really has the ear for a good line,” said Mr Young. “You read the script and you know exactly how the actors will read the lines.

“We are very pleased because this is Billy’s first radio drama. I don’t think there is a precedent.

“It is not often you have interest from actors of that stature, so we are delighted.”

He added: “These things happen because it is all about relationships, and that goes for any business you are in.

“It has made making it happen more simple, because Brian and Billy are excited about it.

“They love the idea of being long-lost brothers who don’t get on.”

The play will be first broadcast on BBC Radio Scotland on Christmas Day and will be on BBC Radio 4 some time next year.

Radio Scotland is a major supplier to the corporation’s radio network, providing productions for Radio 4, Radio 3, Radio 5 and Radio 4 Extra.

Radio Scotland produces between 60 and 65 hours of drama a year for the rest of the BBC.

“It is less well known because there is so little publicity compared to television, but the audiences are there, with drama sometimes getting between half a million and a million people,” he said.

“There is also an incredible loyalty to radio drama: people are drawn to it.”

The radio studio in BBC Scotland’s Pacific Quay headquarters in Glasgow is now a “juggernaut of production”, Mr Young said.

Jeff Zycinski, head of BBC Radio Scotland, said: “It is fantastic news to have two of the biggest stars in Scotland coming together in this very special radio drama which was specifically written for them by Scots writer David Ashton.

“This is a lovely Christmas gift for our BBC Radio Scotland audience to enjoy as one of the highlights of this year’s fantastic festive line-up of programmes.”

Other highlights coming up for the station include a new series of the popular Victorian detective drama, McLevy, starring Cox and Siobhan Redmond.

There will also be new productions of two classic American novels, John Steinbeck’s The Grapes of Wrath and F Scott Fitzgerald’s The Great Gatsby.