LONDON - It started as a joke when 16-year-old Elsie Wright and her cousin Frances Griffiths, nine, took pictures of themselves with paper cut-outs of dancing fairies and a gnome in the village of Cottingley in Yorkshire and claimed that the mythical beings were real.

That was in England in 1917 when superstition prevailed and soon news of their photos went viral, fooling even Sir Arthur Conan Doyle, a spiritualist and creator of Sherlock Holmes, who so strongly believed in their story that he even used the photos for an article on fairies he wrote for a magazine in 1920.

Over a century later, the black-and-white photos which were widely considered to be one of the greatest hoaxes of the 20th century went under the hammer on Thursday at the Dominic Winter Auctioneers in Cirencester, Gloucestershire, for more than £20,000 (S$36,282) - over 10 times their estimated value, the Daily Express reported.

The fairies photo was sold for £15,000 and the gnome photo £5,400 to UK-based buyers.

"We had so much interest and a bank of about eight phone lines but it was the Internet that carried both away without any of the phone bidders getting their hands in the air," auctioneer Chris Albury was quoted as saying by the Daily Express.

"I thought if things went wild we might get to £10,000 for the pair, but these prices are absolutely staggering."