Terry
Sorry for the delay in replying, just got back from two weeks on Gran Canaria when the PC goes on the fritz (only got it back yesterday and took over three hours reloading files etc).
Arch's fourth victory was apparently an Albatros DV destroyed at 16:50 on 10 October 1917 over Moorslede in F2A B1123. The pilot was Lt W G Meggitt and this was his 5th victory (see the entry for Meggitt in
Above The Trenches).
Meggitt is mentioned in the RFC Communique for 11 October 1917 with his observer, Capt F A Durrand. It is possible that this entry relates to the previous day's action and that these two officers were actually pilots. I'll have to have a look and see if I've anything else for this squadron that might shed some light on the matter.
Graeme