Exchange of NCOs

[Howard]

In the WD of 33 Division, para 667 refers to "Exchange of NCOs under War Office letter No. 121/Drafts/5949 (A.G.2) of 23/8/1917"

Does this letter still exist somewhere?

I am interested because my grandfather served in 1 Middlesex then on 27th May 1918 was captured serving with 2 Middlesex. I wondered about the arrangement for transfer or loan of NCOs. He was a corporal (PT Instructor) at the time, but had "papers approved by Col. Page" for a commission lost to the Germans on capture. Initially the Germans listed him as Captain which is odd, I would assume a commission would start at 2nd Lieutenant. The  transfer must have involved leave, my mother was born 8 months after capture.

Howard