Sorry for my late response! Thanks to both of you. It is strange that no matter what source I use, I am unable to find a service nummer. But, he is the only A.A Smith so it must be him.
Hello Jan, The AA Smith that Gus found is in the London Gazette a couple of times. The London Gazette, Supplement 35056, Page 546 Publication Date 24 January 1941 CORPS OF ROYAL ENGINEERS. The undermentioned Cadets, from 141st and 142nd O.C.T.U.'s, to be 2nd Lts., 28th Dec. 1940:— ….. Arthur Albert SMITH (165351). ….. The London Gazette, Supplement 35069, Page 802, Publication Date 7 February 1941 CORPS OF ROYAL ENGINEERS. The undermentioned Cadets, from 142nd O.C.T.U., to be 2nd Lts., except as otherwise stated. 28th Dec. 1940:— ….. Arthur Albert SMITH (165351). ….. Regards, Richard