Thank you both for your help, that gives me a bit of comfort because I was scratching my head aswell to try and figure it out.
I am a bit surprised by the answer as my new lock is for the passenger side! Oh well as long as it works, I don’t mind the extra weight, I guess.
As for the reason for replacement
@Duncodin, my passenger door has always been a bit stiff since I got it in November. I tried all the common fixes, like adjusting the receiving latch height and angle and checking whether the door had dropped, to no avail. Then after a bit of fiddling around I realised the “turny bit” that the receiver goes into was very stiff and I could only just about turn it, having to try as hard as I could, completely different to the drivers side. I tried all sorts of lubrication but it was SO stiff I knew that any manner of lubricant wouldn’t fix it, there was an underlying issue, so I took it out, inspected it and realised it was all pressed together so, not going to come apart easily. So spursfan sorted me out another
Thanks for your help, Chris