The rocky outcrop of islands, only inhabited by sailors in the summer, lies five miles north-east of Jersey.

The unnamed seller of the 800-year-old title Prince and Lordship of Ecrehous hopes to get up to �250,000.

The title has been held in the past by seven kings of England, including William the Conquerer, says the ad.

ECREHOUS The islands were a centre for a smuggling trade between Jersey and France in the 17th Century Philip Pinel, who lived there for 46 years from 1848, called himself King of the Ecrehous A man falsely accused of being a sex offender in Jersey was exiled to the islands for 14 years in 1960

The current holder of the title, a Frenchman, is reported to have bought the title from Cistercian monks in 1976.

Paul Dunkley, of Noble Titles, which is handling the sale, said whoever buys the title would be called Prince of Ecrehous and they could also be buried in the ruins of the Cistercian monastery there.

The holder would also have the rights to hunt on the islands and fish on the foreshore.

He said: "It's extremely rare for the title of prince to come up for sale.

The title comes with a coat of arms

"It is the most expensive title we have dealt with because it is so rare."

Ownership of the islands has been the subject of a dispute with the French in the past.

But British sovereignty over the Ecrehous and a similar reef to the south of Jersey, known as the Minquiers, was confirmed by the International Court of Justice at The Hague in 1953.

The islands, which had been thought virtually impenetrable for leisure boats because of the rocky shoreline, are now a favourite haunt for sailors in the summer.

Up to 50 or 60 yachts can be found moored there in the weekends thanks to improved navigation methods.