Here is a 'possible' answer;
The ends of what you see and call pins are a mix of both 'screws' to hold the bridle in place and 'pivots or axles' on which the various parts pivot.
The two makers may use just the same arrangement of 'pivots' giving the same mechanical action, but a different number of pins (screws) holding things together. For example - the Lancaster has two pins holding the lock plates on whereas the Churchill has only one.
Another possible, though less likely explanation is that some pins are in blind holes (that is to say, they don't come through to the opposite face). I do know that some Churchills were made like this, but I think that either all are blind (except perhaps the tumbler pivot) - or none are. When this is done, they are referred to as 'pinless locks'.
