Celebrities are a rare a sight in quiet little towns in remote Easter Ross. Rarer still is the sound of the most famous pop singer in the world belting out Ave Maria in the local kirk.

But as rumours of the impending nuptials of Madonna and film director Guy Ritchie gather pace, the American pop star has been spotted checking out the acoustics at 776-year-old Dornoch cathedral.

On Tuesday Madonna's private jet arrived at Inverness airport. Surrounded by bodyguards, she was whisked off to Skibo Castle - now the most exclusive club in Scotland.

A few hours later, however, Madonna left the privacy of Skibo for Dornoch town centre and the local cathedral. It was there that bemused onlookers heard her impromptu rendition of Ave Maria.

It seems all but certain that the rumours are true and Madonna and Ritchie will tie the knot in the royal burgh before Christmas. The heaviest money is on December 22 - and the date could be known within days.

If Madonna wants to marry in Scotland she must post her banns at the local registry office within at least 14 days of the big day.

There is speculation that she will marry at the cathedral before holding her reception at Skibo castle - speculation that the local minister, Susan Brown, has not confirmed, or denied.

But as Madonna slipped into Scotland on Tuesday, the tabloids were on her tail and she may opt for a wedding at Skibo castle away from the paparazzi lenses. Skibo castle has long experience in allowing stars privacy: Robert Carlyle married there; Sean Connery and Michael Douglas are regulars.

Ritchie, maker of Lock, Stock and Two Smoking Barrels, has ordered a kilt in Hunting Macintosh tartan in tribute to his Scottish roots. Madonna has been spotted in Paris having fittings at Chloe.