A small notice posted in the register office of the remote Sutherland town of Dornoch yesterday confirmed the world's worst kept secret. Madonna and her film director boyfriend are to marry three days before Christmas.

The announcement for Madonna Louise Ciccone and Guy Stuart Ritchie on December 22 was one of four banns to be displayed, as required by law, by the local registrar, Lesley Connor. "This is the most famous person we have put up on the list," she said. "The interest is nice for Dornoch and good for local businesses."

Within hours every hotel room in the quiet seaside town, population 2,500, was booked. It is thought that the pair will marry at the 776-year-old Dornoch cathedral, with a reception at the nearby celebrity retreat of Skibo castle.

There have also been rumours they may marry at the castle and have their son, Rocco, christened at the cathedral on December 21. Earlier this week Madonna was spotted visiting the cathedral and checking the acoustics with a burst of Ave Maria. Skibo castle was the choice of actor Ewan McGregor and Full Monty star Robert Carlyle for their marriages, and has welcomed celebrities such as Sean Connery, and Michael Douglas and Catherine Zeta Jones. The castle's one time owner, the steel magnate Andrew Carnegie, described the Gothic structure as "heaven on earth."

The tabloids predict that the singer's star-studded reception will have a Braveheart theme, with straw scattered on the castle floors for a mediaeval banquet and waiters dressed as Scottish warriors.

Yesterday, as journalists trampled up and down Dornoch's main street trying to uncover details of the event, shopkeepers and residents appeared unperturbed. "It certainly makes the place busy," said William MacDonald, the ironmonger-cum-florist. "Personally, I don't see it as any big deal. Dornoch was here before Madonna was born and it will be here long after she's left." And, said one man: "I'm still waiting for someone to tell me who Madonna is. I thought it was a painting by Leonardo da Vinci."