Billy Connolly is to join wife Pamela Stephenson on a televised quest to trace the routes of her great-grandfather.

Samuel Stephenson – a master mariner nicknamed Salty Sam – vanished in 1821 aboard his trading ship.

Now Australian-born Stephenson has retraced his last voyage across the Coral Sea for a four-part Sky One documentary, Murder Or Mutiny.

Connolly will accompany his psychologist wife on a dive to try to find the wrecked ship.

The shows are due to air in late autumn, and Stephenson will also turn her adventure into a book, hoping to follow the successes of her biographies of Connolly.