THE heroine of the best selling novels of Alexander McCall Smith, the No. 1 Ladies' Detective Agency, is heading for the stage.

The writer, speaking at the Edinburgh International Book Festival, revealed he is making the books into a musical, with music by Graham Weir, a former member of Orchestral Manouvres in the Dark (OMD).

A story about the heroine of the books, Mma Precious Ramotswe, confronting a witch doctor will be at the centre of the musical, he said, in a work which will be set in Botswana.

Three songs from the show were revealed to the packed audience at the festival in Edinburgh's Charlotte Square.

McCall Smith said: "We working on a musical, which is very exciting,

"We are in the early stages of the project, and Graeme has been creating the most wonderful music for it.

"The situation is quite complicated because the rights of a stage version of Mma Ramotswe are controlled 50% by me and 50% by people in the United States, so we are exploring ways we can get this together, but we are making very good progress."

There have already been adaptations of the books, which have sold more than 5m copies.

The BBC and American television network HBO filmed a series based on the books that starred Jill Scott as Mma Ramotswe and was shot on location in Botswana.

The pilot was written by Richard Curtis and Anthony Minghella, who also directed.

McCall Smith dramatised the series for BBC Radio 4.

Thirty-one episodes have been broadcast, the first on 10 September 2004, and the most recent on 5 August 2016.

The episodes encompass the first to the sixteenth books. They star Claire Benedict as Mma Ramotswe.

Mr Weir said: "Sandy and I put our heads together, and we think it is going to be popular.

"The key thing is that we are not setting up ourselves against The Lion King.

"I have been writing the songs and sitting with Sandy for hours on end, and as you know he is a garrulous man with many stories to tell, but eventually after many long hours we tease out ideas to set to song."

One song was called Ladies of Traditional Build while others dealt with nature and the machinations of the Witch Doctor.

McCall Smith added: "The musical is a celebration of love and friendship, and understanding."