Buckingham Palace is to hold urgent talks with ministers over its fears that the Queen's head could vanish from British stamps following the Government's sale of the Royal Mail.
There is no stipulation in the Postal Services Bill, which privatises the service, that the image should be included on future stamps. The monarch's head has been on every stamp since the Penny Black of 1840.
The Bill could result in up to 80 per cent of the Royal Mail owned by a foreign company.
Vince Cable, the Business Secretary, acknowledged the loophole, and said: "We will talk to the Palace about whether any further changes need to be made."