The Oxford and Cambridge Club, one of the UK's most exclusive clubs, has suffered a major data breach after a backup computer drive containing members' personal details was stolen from the club's headquarters in Pall Mall, central London. The club has written to its 5,000 members urging them to monitor their bank accounts for any suspicious activity after a small computer drive, about the size of a toaster, was taken from a locked "comms" room inside the club's headquarters.

The data stored on the hard drive included members' names, home and email addresses, phone numbers, dates of birth, photographs and some bank account details. Credit and debit card details were not stored on the hard drive, according to the club, the Telegraph reported.

About 100 staff members' data was included in the database.

The club draws its membership from the alumni of England's two historic universities. Some members who may have been affected by the breach include actor and comedian Stephen Fry and Lord Rees of Ludlow, the Astronomer Royal.

However, Prince Philip and Prince Charles - both of whom are honorary club members - were not affected by the theft that was discovered on Thursday (16 November).

"We have been advised that we should write to confirm that there may have been a data breach at the Club which could possibly result in disclosure of your personal data held on the Club computer system," the club's secretary Alistair Telfer wrote to the club's members via email and letter.

"This situation has arisen as a result of the theft of a storage disk, and not as a breach of the cyber security system, and although the data contained on the disk is protected by multiple layers of security and heavy password protection, we have been advised by data specialists that there is a very remote chance that information could be obtained.

"As this could potentially enable identity theft, the management felt that members should be informed as a duty of care. The management team would like to extend their apologies for the inconvenience caused by this unfortunate incident."

The club has contacted the Metropolitan Police and hired private investigators to look into the theft and breach. Police are currently examining CCTV footage at the club and checking records to see who entered and exited the club.