Only nine watches of the Richard Mille RM 030 Carbon Kronometry AN CA 1999 were manufactured by the luxury Swiss brand.

However, the seller is so afraid of “shotgun-toting gangsters” stealing the timepiece from Rowley’s Auctioneers, in Cambridgeshire, that he has refused to hand it over until after the sale.

Bidders will instead have to rely on photographs presented at the auction on Saturday.

The successful buyer will then meet the vendor at a Richard Mille branch in Bond Street, London.

Once the watch is officially verified by experts at the shop, the buyer will send a “pre-agreed codeword” over the phone to Rowley’s to approve the transfer of funds.

Roddy Lloyd, managing director for Rowley’s, said the cloak-and-dagger approach of the sale was highly unusual, but the only way to make the sale happen.

He said: “It’s very uncommon. It has never happened before, not with us anyway.

“It is such a vulnerable item, because it’s small.