Thank you very much for drawing my attention to this. It gives a very clear picture of the battalion's role in the battle - and to the dreadful conditions in which they were defending. I will send it to Arthur's other surviving relatives. I'm very grateful for your time.
The newspaper article describes the battalion's heroics efforts during the second battle of Ypres, many were gassed.
https://www.barnesfamilyhistory.org.uk/firstworldwar/gallant_east_surrey.htm
The Menin Gate commemorates those soldiers who have no known grave - about 54,000. Conditions were dreadful and it would have been unsafe to collect some of the fallen from the battlefield without further endangering lives.