His papers refer to him as Henry James and Henry John but he was definitely Harry John
Yes, I have relatives with the same problem - Grandpa was registered as "Jack" but was continually having his entries 'corrected' to "John"!
So - Harry John.... These are my additional comments:
Note that he attested 11 Dec 1915 but was not actually called up until June 1916. This means that he volunteered under the Derby Scheme - people knew conscription was coming and by volunteering now, they could choose which regiment to join. After volunteering and attesting, they were put into the Army Reserve and allowed to go back home until actually called up / mobilised.
Original no. 26278 will be a Royal Berks number.
15/6/1916 - mobilised - i.e. called up. Posted to the 3rd Royal Berks on 17/6/16
4/7/16 Appointed Lance Corporal. At the time, lance corporal was an appointment specific to a unit, not a permanent rank - hence he is appointed, not promoted.
11/10/16 Posted to 46th Infantry Base Depot.
18?/10/16 at Rouen from 46 Infantry Base Depot
21/10/16 Posted to 2/4th Royal Berks and allocated no. 20296 (this is a Territorial Force series number as he's now in a different sort of unit so needs one of their numbers).
I think that 202992 is his later Royal Berks number under the 1917 TF Renumbering.
27/4/17 - transferred to 1st South Midland Field Company, Royal Engineers Territorial Force, and posted to 31st Road Construction Co.
Sounds as if the Field Company took them first and then sent them to other units such as Road Construction Companies.
Needs another new number - 495916 - which is a number applicable to 1 South Midland Field Co.
Note he is transferred over as a Private, not Lance Corporal. The RE doesn't have Privates, it had Pioneers (semi-skilled) and Sappers (skilled). I think that he becomes a Pioneer.
Note that although it says "Date of Casualty" this doesn't mean he was wounded - "Casualty" originally had a much wider meaning of being taken off one duty and put on another.
21/11/17 - Appointed Acting Corporal (Paid), then promoted corporal from the same date - this was possibly backdated because otherwise the dates and references make no sense.
5/5/18 Remustered as a Road Foreman - note this is a role, not a rank.
At some point he is renumbered WR/30828 - the WR/ numbers were used by Water and Rail companies - and roads as well it seem! I'd not heard of Road Construction Companies before - I'd guess that yes, they were building roads but quite possibly anywhere in France or Belgium where the roads needed improving for the war effort, not just immediately behind the lines.