From the obituary:
"Robert Frederick Hitch (the grandson of Pte. Frederick Hitch VC of Rourkes Drift) was born on the 16th. July 1916 and followed his grandfather and father into the South Wales Borderers on 6th. November 1934. Bob Hitch served on the North West Frontier and Malaya and after being appointed WO1 in 1958 was posted as the R.S.M. at A.A.J.L.R. In 1963, he was Commisioned and served in Hong Kong and the Junior Tradesman's Regiment Troon, before retiring on 8th. October 1970 after 28 years and 201 days service."
I'm not sure how that works. I know the Welsh are not renowned for their ability to count, but they seem to be about seven years out with this one. Were they maybe trying to diddle him out of some pension? I make his service as 35 years and 336 days.
I underlined a bit in your post, its possible those missing 7 years were from when he commissioned.