Hi there.
A quick glance at John Dormer's service record shows him as enlisting on the outbreak of war and being posted to the 1st Battalion in France in March 1915. He then suffered a bout of influenza and a spell in hospital, then rejoined his battalion.
1st Ypres was in 1914, so John would not have been there for that battle. 2nd Ypres took place in the spring of the following year, officially ending May 25th. John may well have been involved in that second battle - he would certainly have seen action at Ypres around the time of his death.
"The Historical Records of the Buffs 1914-1919" by R.S.H. Moody has a reference to John Dormer.
"On 2nd July Corpl. John Dormer of A Company, who had covered himself with glory as a scout, paid the last penalty."
There is obviously some error with this as rank and date of death do not tally. It seems possible that, although John Dormer is definitely mentioned by name, he may be confused with Corporal L. Dorman of the same battalion who DID die on 2nd July 1915. Although soldier's names do not often appear in war diaries of the time, perhaps this is one of those rare occasions and may clarify this. It would being interesting to know which is correct.
I hope you are managing to find all the information you need,
Regards,
Scobie