Der! I dont know why I didnt look in my 'other' archive! I have stacks of dambuster related photos and several clearly show RCAF Flight Sergeants (Don MacLean, Ken Brown etc) wearing brass crowns. Although they were no doubt Brit issue, it shows RCAF did wear them.
It was actually Warren who had told me they didnt wear them. So was it simply a case of them being worn outside Canada as local issue or does anyone have photos taken within canada of them being used?