Thank you CandyGuru. Unfortunately I didn't see the PF symbol so I peeled up the stupid relabel. It contains nuts if it is from the UK.
yes, all the Canadian ones have that peanut-free logo, so if there is no logo, it's not from Canada
yes, unfortunately, the UK Mars bars may contain tree nuts
if you ever have friends/co-workers visiting Canada, you should ask them to pick up some Mars bars for you