I'm glad that your quest was successful. You asked about abbreviations. The first significant one comes in the authority for his posting to Eastern Command. APM stands for Assistant Provost Martial - a staff officer in Headquarters of VP Wing.
Y list is an administrative holding position while a soldier is non-effective due to illness in hospital over 21 days. The significance of him being on the Y list was that his parent unit could ask for a temporary replacement to keep them up to their war establishment. It was not a posting as such and in most cases the soldier would return to his previous unit after coming off the Y list (assuming that his fitness level was suitable).
E5 was the lowest grading for a man who had been assessed as permanently unfit for service. The grade 5 represents the extent of his physical limitations, such as strength, endurance, mobility. It might also reflect visual or hearing problems.
In 1940, a system of categories was selected by the Army as follows:
· A1, A2, B1, B2, B3, B4, B5: These seven categories were based on vision in relation to shooting and driving, physical endurance, the ability to march and the manifestation of any other disease which would affect military duty. The categories also had caveats which determined both task and location worldwide.
· C: Home service only.
· D: Temporarily unfit.
· E: Permanently unfit.
The Army allocated a soldier to one of these categories
on the basis of the Civilian Medical Board grades.
Source: Fifty Years of PULHHEEMS—The British Army's System of Medical Classification by Col T P Finnegan, MSc, FFOM Colonel and Deputy Assistant Chief of Staff (Medical) Headquarters, Land Command, Wilton, Wiltshire, UK published in Annals Academy of Medicine September 2001, Vol. 30 No.5.
The 'unconnected' bit means that his disability was not attributable to his military service.
And yes some VP CMP companies were posted to North West Europe where they were employed guarding prisoner of war camps (see Wikipedia article
History of the RMP).