A recent Sotheby’s auction of 20th-century stamps from the British Postal Museum & Archive’s (BPMA) collection has fallen far short of expectations, with just 29 out of 191 lots sold.It was hoped that the sale of the duplicate stamps earlier this month, which had been approved by the Museums Association's Ethics Committee , would raise an estimated £5m towards a new museum in central London to house the BPMA’s permanent collection.But the final total for the auction came to just £400,920 - less than 10% of the hoped-for amount - with every lot sold failing to reach its estimated value. The highest individual sum raised was £192,000 for a set of stamps dating from 1918-19 with an estimated price of £260,000-£320,000.A spokesman from Sotheby’s said: “The sale was presented to the widest possible audience and with appropriate estimates, but the British stamp market did not support this historic opportunity to purchase rare and important stamps."The auction had been hailed as “the most important archival sale of stamps ever to take place”, featuring material from the reigns of King George V, King Edward VIII and King George VI. The most valuable set was given an estimated price of £400,000-£500,000.The spokesman would not comment on why the sale failed to live up to its billing, but the auction was dealt an advance blow when the leading stamp dealership Stanley Gibbons Ltd confirmed that it would not be attending. According to Sotheby's, the buyers at auction were predominantly private collectors rather than dealers.In addition, the BPMA’s decision to dispose of the items had attracted strong criticism from philatelists.In a letter earlier this year to the Antiques Trade Gazette, postal historian and collector Gavin Littaur slammed it as a “fire-sale” and called on the BPMA to ensure that unsold material would not be “offered at increasingly discounted prices”.Other collectors had raised fears that the sale would undermine prices by flooding the market.Sotheby's confirmed that, as part of the standard process, it would continue to accept offers on the unsold material on behalf of BPMA “if there is an agreement to do so”.A BPMA spokeswoman said: “Following the results of the sale, the BPMA remains committed to delivering a new postal museum for the nation and is working hard with Sotheby's to ensure the post-sale process results in the best possible outcome to support our project.“We remain confident that by following this process, Britain's rich postal heritage will receive the first-class home it deserves.”A further auction of duplicate material from the museum's collection is due to take place in February 2014.