I have a 2010 Smax 2.0TDCI which only doe around 5000 miles per year. I needed some new tyres, and decided that it would be worth changing the TPMS valves at the same time, since the batteries would probably die before the tyres needed changing again (at this point, the system all worked fine).

The tyres and valves were fitted by a local garage, with the valves sourced by the garage from the local ford dealer (genuine ford parts at nearly £90 each!)

Since the valves were changed none to the TPMS system works. I get a message saying TPMS not detected, but using the garages TPMS tool, I can see all the sensors appear to be working, and the car has the correct serial numbers in the correct places.

The ford garage who supplied the sensors has had checked the car over, and have told me the Body Control Module has failed, and quoted £1000 plus to replace it.

It seems to me that it would be an enormous coincidence if the BCM happened to fail on exactly the day that the new valves were fitted. Does anyone have any thoughts about possible other causes, or if the BCM has failed, what would cause it? I am completely at a loss as to what to do next.

It does sound too much of a coincidence. Dont suppose you have the old ones to hand (very long shot)

I agree, it would be very unlikely that the BCM would fail only on TMPS and on the day the valves were changed. Most probable fault is that they are the wrong valves for your car. As already said "do you have the old valves"?