Thanks John.

Someone came back to me from the www.bravenet.com WFA site and advised:

55th Division held a sector south of Arras, from Wailly to Bretencourt from 16 February to 25 July 1916 when they moved south to take part in the Battle of the Somme, which explains why Pte Cowley is remembered on the Arras Memorial. I am not sure exactly where 7th Kings were on 3 July, but the war diary in the PRO would tell you where they were & what they were doing. 55th Division do carry out a number of raids at this time as diversions from the Somme sector. 55th Divison were meticulous about recovering their dead if possible (see their plot in the cemetery at Wailly) and so I would guess that Cowley was killed in a raid or patrol & it was not possible to recover the body, although perhaps he was buried & the grave lost later in the war. You could try the Kings Regiment Museum; their web-site has a guide to researcher a relative in the Kings Regiment. http://www.nmgm.org.uk/liverpoollife/soldiersframeset.html

The site was very useful and I will plan at least a day trip to Liverpool to do some further research this summer but if you have any information in the meantime I'd love to hear from you.

PS Another person came back with the following suggestion which I've taken up.

Try the soldiersdied web site http://www.kev84.worldonline.co.uk/soldiersdied.html a new site I found by accident and who came up with some wonderful information about my Great Uncle who I am researching at the moment