Thanks for replies. Its deffo 100% NOT wheel bearing. When we switched the wheels back to how they were before we swapped front to back, the "problem" went away - Its almost as if there are 2 different types of wheel - one for the fronts, one for the rears. ( As I said before the wheel rims look identical) The car normally wears its tyres very evenly so in 8+ years we have never ( to my memory) swapped the wheels front/back.
With the wheel off you can see the calliper unit. In very broad terms it resembles a thick paperback book. If you align the book so that the spine is the outer edge, its this outer edge for the full length of the book that's marked. ( both on the spine and on the "cover" - its about a 10mm graze) The wheel is marked literally 2/3mm beyond the largest circular point where the round holes are punched out.
I can see where you are coming from re pad thickness of Non-Honda items, and this could well be the issue. The fact no one has chimed in that this is a Jazz peculiarity, makes me think even more the pad thickness is the problem.
I think I have some spare wheels that I was going to fit snow tyres to, I'll try these out tomorrow/later in the week and let you know how I get on.
Cheers
Bob