Dating from the 1st World War, for use with wire lug wristwatches.
Sprung nickel watch protector as sold by John Warrillow Ltd, Birmingham. Their 'Standard' pattern, for all early wristwatches other than Ingersoll - see their advert, a copy of which I show. No 2 size, 35 mm diameter, intended to cover the watch completely.
English Patent No 13590, 1915, John Warrillow having the sole license to manufacture them. Designed for and advertised to soldiers and sailors in the military and regimental journals of the day. See also the article by the late Dennis Harris 'Wrist Watches 1919-1920 (An introductory study)' in the Summer 1988 issue of Antiquarian Horology, still the best and most accurate overview of the subject.
Some light scratches and wear, as to be expected, otherwise complete and with good strong spring action.
Warning: Last items in stock!