The Pioneer Corps are an unsung unit of World War Two. Many men who enlisted in the Corps did so as much of their duties were non combatant as some were conscientious objectors. Other were actually German or Austrian nationals who, at first, were not allowed to fight. The Corps performed hard physical work building military baracks, digging trenches, etc.
My Great Uncle served in the Corps in WW2. He was a Sgt. He only got to serve as far away from home as Birmingham! But he had a famous footballer in his Platoon named Billy Wright. British forum members will know the name.
After the War they were given the "Royal" title by the King in recognition of their hard work.
The design of the badge with a crossed rifle, pick and spade reflexs well the role of the Corps. Note the rather bright yellow colour to the brass "gilding metal" metal used in the manufacture of this badge, which is typical for many WW2 badges.