WW2

This is a WW2 52nd (Lowland) Division formation sign: a white St Andrew's saltire on a blue shield with a black border. The division adopted this simplified saltire-on-blue-shield design in 1940, replacing its First World War badge, and added a separate "MOUNTAIN" scroll around May 1942. There's no scroll with this one. 

The maker's backing is the interesting part. The canvas reverse is stamped in blue "Wm. Anderson, Military, EdinburgH. Scotland.

William Anderson & Sons were Edinburgh military outfitters who made officers' uniforms for all the Scottish regiments. That, plus the woven construction, makes this a private-purchase or tailor-supplied piece rather than standard issue. From December 1941 the official uniform patch was printed cotton (Ordnance issue).