Begging letters from the Prince Regent to his father George III have aroused just as little interest today as they did in the 18th Century.

A series of correspondence from 1785 to 1795 showed the King becoming increasingly frustrated with his errant son.

More than 30 drafts, notes and memoranda were in the collection auctioned by Sotheby's in London yesterday.

It was expected to sell for more than £15,000. But the lot was withdrawn after failing to meet its reserve price.

Manuscript expert Tessa Milne said: "Unfortunately, the lot did not sell. The other letters were all sold but the top bid for this was £9,500, which was below the reserve. It's a shame, but one never knows at an auction. It usually works in the seller's favour but not in this case."

The letters provide an insight into one of Britain's most bizarre royal relationships.

One letter reveals the Prince, who helped shape the history of Brighton, allowed £110,000, the equivalent of £8 million today, to slip through his fingers with "no explanation".

The collection, which will now return to its owner, also includes a memorandum signed by merchant banker Thomas Coutts asking for repayment of a loan for £54,267.

Other documents show how the King and prime minister William Pitt tried desperately to curb the extravagant spending habits of the Prince.

At one stage, the King refused to see his son and resorted to sending letters through a third party.

One message from the King to Pitt reads: "The shorter the message in answer to the letter from the Prince of Wales can be, the less room is there for it not being understood."

The collection was described as a "real blow-by-blow account" of a father-son relationship.

But collectors were not impressed.

Other lots sold well, however, with a self-portrait by Rembrandt, discovered last autumn, being bought by a casino magnate for £6.9 million.

American Stephen Wynn bid by telephone for the masterpiece, which he will display in Las Vegas.