Help Required re. ID of Military Unit

[Bob Moseley (RIP)]

Hi All
A mate of mine has restored an LP1 Bren Gun Carrier. Whilst undertaking this he found three names and a possible Army Unit written in pencil on a seat back. The unit apears to be 1 RVC and the names are McDonald J.O, O'Brien A.A and Mansfield, R.W.D. I am in the process of identifying the names and have narrowed down the possibilities. The ultimate object of the exercise is to identify the hull number of the Carrier and contact any of the three if they are still alive. I believe RWD Mansfield is deceased, however the other two may still be around.
Bob