1918 rare early round silver vintage Rolex watch

A rare early round silver vintage Rolex watch. The large case measures 34.5 mm in diameter, with hinged lugs. The case is signed W&D (Wilsdorf and Davis), Rolex Swiss and hallmarked London 1918. The movement is signed Rolex with 15 jewels and has centre sweep seconds. The white enamel dial, with a sunken centre,  has black Roman numerals, with a red twelve. The dial is signed Rolex above the centre.

This is a very rare, early example of a wristwatch with centre sweep seconds, in very good condition.