I think it would be unwise to proceed on the basis that he joined the 1st battalion because some other local inhabitants did, without further evidence. There was a total of 12 battalions of the Hampshire Regiment during the war, six of which served overseas. Three of those which remained in the UK were converted to other capbadges, one becoming a Royal Artillery Anti-tank Regt and two joining the Royal Armoured Corps.
If it helps, there was a Pte DH Elms in the 2nd battalion who was taken prisoner in 1942 in North Africa; a Sergeant IS Elms of the 7th battalion who was wounded in Groesbeek-Mook area on the Dutch-German border on 4 Oct 1944, and Pte SE Elms was killed in action with the 2nd battalion in Italy on 13 October 1943.