My Grandfather was killed in Eau Court Sur Somme on May 21st, 1940. What was engagement that he was killed in.

My Grandfather was a Serjeant in the Queen's Royal Regiment (West Surrey). He was killed with two other soldiers and is buried in a churchyard in Eau Court Sur Somme (Commonwealth Graves Commission, great well maintained website). I want to find information about his regiment and what he was doing when he was killed. I have read many magazines and newspapers from that time but have not been able to identify his unit in any of them. My question is are there resources I can examine to find out more about him and his unit. Thanks in advance for your help as this is very important to me.