Nice little end to my saga on this subject - another "Good". I sent for replacement spare winter tyre from Mytyres and it was delivered the following day (today. This time I had no hesitation in whether to order a spare or not.

Shame they can't be integrated into the valve stem to stop low life taking an interest in them. Definitely better system than we have though.

I got the impression that the sensor/sender was on the inside of the wheel rim with just a normal looking valve stem visible.

Thats why they have to be fitted with the tyres removed (which is an extra expense of course).

I think the batteries have a seven year life span though.