Appointed as a Stoker 2nd Class (No.KX179007), and sent to the training establishment H.M.S. Duke at Malvern, Worcestershire. On 17th April 1943 he was drafted to H.M.S. Quebec the Combined Operations Training Centre at Inverary, Scotland, where combined operations training took place, usually on the shores of Lock Fyne.

He was shipped out to the United states of America whilst on the strength or H.M.S Copra, and was one of the crew appointed to the Landing Craft (Tank) 7007 going aboard her straight from the builders and following a brief work-up the vessel sailed across the Atlantic to the United Kingdom. It must have been quite a trip as this type of craft could only manage 11.5 knots at top speed. 

Harold was to serve aboard LCT 7007 until his demobilisation in December 1946 LCT 7007 was part of the 15th L.C.T. Flotilla operating in Home Waters and based at the LCT base at Dover, his pay base being H.M.S. Copra (Combined Operations Personnel Records & Accounts) in Largs, Scotland.

LCT 7007 was involved in the D-Day landings on 6th June 1944 landing tanks, troops and equipment, and is believed to have been assigned to Gold beach. Dutton had been promoted to Stoker 1st Class on 15th February 1944 and was appointed Acting Leading Stoker on 15th February 1945. After the invasion of Normandy, LCT 7007 continued to ferry troops and supplies across the Dover Straits and other sectors from the south coast of England.