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The improvements mean that the auction room can now prepare for one auction while holding another.

The two sales, one on September 13, the second a two-day event starting six days later, both offered interesting items associated with U-boats.

First up was a submariner's pocket depth-measuring device, c.1940, which came in from a local consignor and, estimated at £100-150, sold for £650.

Perhaps more interesting was a rare German military pocket watch which was destined to be 'handed to the grandchildren to play with' before being spotted by Wellers during a valuation.

"Pulled from a box of costume watches, this rare International Watch Company (IWC) military pocket watch came as a huge surprise," said Wellers' jewellery specialist Elliot Franks.

"It was one of only 1000 pieces commissioned by the Kriegsmarine [German Navy] and this navigation watch was one of a few surviving pieces - the majority resting at the bottom of the sea.

"Many of the surviving watches were redesigned by IWC after the war. This piece, numbered 'M17945 II.KL', was actually one of the first 400 made."

Its original state - it retained the marks and dial that the redesigned pieces had removed and replaced - made it an even rarer prospect. It was also in working order. Estimated at £1800-2200, it sold at £1900 plus 20% buyer's premium.