The cap badge is an officer's cap badge. 3PWD was a Peterborough militia cavalry unit that was disbanded and then amalgamated with The Peterborough Rangers, Headquarters and "C" Company of the 4th Machine Gun Battalion, Canadianicon Machine Gun Corps, to become The Prince of Wales Rangers.
Probably affiliated with the 3rd (Prince of Wales's) Dragoon Guards of Englandicon. Same cap badge.
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