Apart from personnel matters, some information about the railway vehicles mentioned and shown above may be of interest to the members of this forum.
Firstly, a slightly better version of the photo of Ambulance Train No. 51, taken on athe line to Jeruslaem, probably around the middle of 1918, after that line was regauged by the British Army to Standard Gauge. AT 51 started operations in the Sinai as No. 9 Ambulance Train, EEF, in June 1917, and was the second of 2 such trains provided by the London & South Western Railway Co. (the other being No. 6), both of which fulfilled similar duties. It was briefly renubmbered as No. 46 in January 1918 before gaining its final number in the global WD ambulance train series, as AT 51 in February 1918.
The 12 vehicles of both trains were later converted back to civilian use by PR, and two survive (in much rebuilt form) to this day, one of them in The Israel Railways Museum, restored to 1930s 3rd class condition. The train engine in the photo is one of a large group of L&SWR 'Adams 0395 Class' 0-6-0 steam locomotives brought the area during the war, most of which also served with PR.
Hijaz Railway (HR, and note official spelling) saloon carriage No. 80 was originally built in 1906 by the German company MAN - see works photo below. The date of its conversion to a saloon is not known, but it was "sold" (i.e. scrapped) in 1933. This is in fact the first photo I have ever seen of this vehicle after conversion to a Saloon, and I am very grateful to the OP for sharing it.
Obviously, as No. 80 was a narrow-gauge carriage, it would not have enabled JP Graham to tour the "entire system", and was probably used by him mostly in his capacity as resident superintendent of the Transjordan section of the Hijaz Railway part of PR, plus the occaisonal trip to the PR headquarters in Haifa.
I will deal witt the various trolleys shown in a future post, spare time permitting.