Antony van Leeuwenhoek, the Dutch father of microbiology, made more than 500 microscopes some 300 years ago. Each was little bigger than a postage stamp and all but nine have since disappeared. Of those, at least one is probably a copy.

All the others are in museums, with one remaining in private hands. It was owned by Dr J J Willemse of Rotterdam, who found it in a box of laboratory impedimenta he purchased from the Zoological Department of Leiden University in 1978. The little microscope, less than 40mm long, had once been in the collection of R T Maitland, Director of the Zoological Gardens in The Hague, and its rediscovery amongst oddments in Leiden thirty years ago was a remarkable event.

Estimates of the sale price had ranged up to £100,000. Brian J Ford, the authority on Leeuwenhoek, said the sale was the most dramatic he has attended. “Many items sell in a matter of seconds, but this one lasted a tense five minutes,” he said. “It began slowly, at £45,000, then £48,000. Most of the bidding came from the Internet and by phone. At £200,000 it stalled, but it picked up again and reached a total of £321,237.50 – the buyer it still a mystery.”

European museums and private collectors were among the challengers. “The Deutsches Museum in Munich owns two of the silver microscopes” Professor Ford says, “And from what I could hear from the telephonists, I believe they were among the highest unsuccessful bidders.”