The Bren Gun
According to the web site Canada at War this is Private H. E. Goddard, of the Perth Regiment, carrying his Bren gun as he advances through a forest north of Arnhem with the 5th Canadian Armored Division. Photo via Wikipedia.
WWII Version Chambered in .303 British
Post WWII Chambered in 7.62×51
Produced in the Inglis factory for Canadian and allied forces.