This well-worn clasp knife, with can-opener blade, was a typical armed forces issue (hence the arrow mark and 1940 date).  Such knives have survived in some numbers and were contracted by the government from a variety of Sheffield makers.  ‘L. Wilson’ may denote Lawrence Wilson (1890-1961), whose father, Thomas Wilson, owned a cutlery business.  For further details, see the profile of Thomas Wilson (Sheffield) Ltd.  In the 1930s, Lawrence Wilson sold tea pruning knives, machetes, and plantation pangas.  He also developed links with Birmingham makers.  Although Lawrence Wilson eventually concentrated on tool manufacture (later establishing Gordon Tools), it is possible that he executed government orders for military knives.