Blackadder,
What you have is the shoulder insignia of the 1st and 2nd Canadian Infantry Battalions, RCIC, which existed from 1951 to 1953. When the PANDA force was created for NATO service its personnel were recruited through existing militia regiments. The original force, from which the 27th Canadian Infantry Brigade Group was created, had three infantry rifle battalions; the 1st Canadian Infantry Battalion, the 1st Canadian Rifle Battalion and the 1st Canadian Highland Battalion. Each battalion drew their personnel from five militia infantry regiments of the same type (line, rifle or highland). Each militia regiment formed a complete company within that battalion with the headquarters being a composite. The individual companies wore their parent regiment's uniforms and insignia which required a complete uniform change for an inter-company transfer.
To provide a common insignia for a multi-uniformed battalion each wore a shield device on both arms. The centre device identified the individual battalion; a bayonet for the infantry, a thistle for the highlanders and a bugle horn for the rifles. When the second battalions were raised for reinforcements the devices were retained and used. In 1953 the battalions were redesignated as The Canadian Guards, The Black Watch (Royal Highland Regiment) of Canada and the Queen's Own Rifles of Canada, and the devices ceased to be used.
Check out Army Historical Report No. 51 at the DHist website. It details the history of 27th CIBG and is available online. It lists the 15 militia infantry regiments that contributed to the brigade group, along with those that created the remainder of the units.
Also, thanks for the photo of helmet use in Korea. First ones I've ever seen.
Cheers,
Dan.