The unique Bible used by George III to swear his Coronation Oath is in danger of being lost to the nation after the failure of an eight-year attempt by the owners, Asprey's, to sell it.
Yesterday Asprey's was temporarily refused permission to export the heritage item to the United States in the hope that a British buyer would come forward before the 13 September deadline.
But negotiations with the Victoria and Albert and the British Museum have come to nothing and it is feared that Asprey's will be granted permission to sell the Bible abroad if no British buyer emerges.
The Bible, engraved with the royal arms and valued at pounds 350,000, was the testament on which George III - recently immortalised by the box office hit film The Madness of King George - swore his coronation oath in 1761.
It has been used as a royal scrapbook, and the signatures of every monarch from Queen Victoria to George VI have been pasted in. A member of the Osbaldestone family, the then Bishop of Carlisle, owned the Bible when it was used during George III's coronation.
It then passed into the Mitford family and later descended to Lord Amherst of Hackney.
"This is probably the most important piece of heritage that Asprey's have handled to date. We do appreciate that it is very important and would prefer to see it kept in this country," Charles Truman, a director of Asprey Antiques, admitted yesterday.
"But we have offered it to a number of institutions and we didn't get anywhere. We've applied for an export licence to take it to the New York International Fair in October. We would obviously like to see the situation resolved by then."
The decision by Viscount Astor, the heritage minister, to put an export stop on the Bible will be reviewed after 13 September in the light of any offers to the Department of National Heritage.