Nothing I can see gives any clue to secret work but obviously there must have been times when he was involved in handling "mystery" items in the docks.
His medals as listed are, 1939-45 Star, Africa Star with either 1st or 8th Army clasp, Italy Star, (since he was involved with Operation Husky, the invasion of Sicily), the Defence Medal and the War Medal.
It would appear that he was also involved in the evacuation from France in 1940,not necessarily from Dunkirk however.