With the new King, came new stamps bearing his portrait.
Canada was one of the first countries with new stamps for HLM King George VI. On April 1st, 1937, the definitive set bearing the new King's portrait was released. In April and June, 1937, the coil stamps were released in the same design.
Here are the coil stamps:

These stamps (my favourite King George VI stamps) were nicknamed the "Mufti Series". Why? The term "mufti" is an Anglo-Indian term meaning (loosely translated) "street clothes". In the Canadian and British Commonwealth Armed Forces, the term mufti is used to describe wearing shirt, tie, and jacket, rather than uniform dress, for a particular function.
The usual tradition of stamps in the Empire & Commonwealth was to portray the King in his full uniform. Breaking with tradition, the Canadian Post Office Dept. released the first set of stamps for the new King, in "mufti".
The stamps are seen on a great many covers for the first part of the Second World War. The 3-cent carmine stamp payed the domestic letter rate. Over 1 Billion of them were printed! Wow!
The stamps were in production until the release of the War Effort Series, in 1942.