The cost of the rarest books is starting to rise just as ebooks chase paperbacks off the shelves, thanks to web searches. Matthew Haley, head of the books, manuscripts and photographs department at auction house Bonhams in London, said the rise of online catalogues and aggregators of booksellers' stock meant more collectors were aware when a rare find came on the market.

Haley told an audience at the Hay book Festival, more people can find it, want it and know that there is only one of them around. He said that demand was growing for what he termed "quirkiana" or books on specialist, niche topics that normally would not sell well. The difficult market is the mid-rank with books between 100 pounds and a thousand.

These are books which are rare but not unique, and modern first editions as potential purchasers could scour the web for other examples more easily than in the past. It was starting to look that second-hand bookshops were doomed, he said. Haley said some in the industry forecast digital books would outsell printed books in Britain in 2015. Yet the shift to digital publishing only made physical books more alluring to many people.