I’m lead to believe that here in New Brunswick, a class one entitlement expires two years after you fail to renew your license after the expiry date on the license, ie when you need to do your medical etc. So for example if my license runs out on the 15th of June 2016 and I didn’t complete the medical or wasn’t even in Canada such as yourself, you’d totally lose the entitlement on 15th of June 2018, but any time within the two years you complete and submit the forms and medical you can have it renewed. Very different to the UK where once an entitlement is awarded, it never expires as such and your license merely remains dormant for 10/20/40 years etc until you submit the necessary forms and medicals and its re-issued in its entirety.
Your UK license has no bearing on it whatsoever as vocational entitlements do not have any sort of bi-reciprocal agreement. If Alberta is the same as NB, once you lose the entitlement you’d have to retake the test to have it reinstated. This may well differ widely between provinces.