On 16/04/2019 22:22, RJH wrote:
* Yale branded bought on ebay, came in what seemed to be Yale box with
Yale marked keys. But I think it could be a fake, if only because it's
always felt less smooth than an identical lock on another door, and it
lets draughts through the 'key hole' (the other doesn't).

I have plenty of spare euro locks from the time I was in to lock
picking as a hobby.
Interestingly enough when the key would only turn approx a quarter turn
thinking it was maybe the key I did manage to pick it with the same result.
Thats when I decided it was not the euro lock that was the problem.