Yes exactly, that's why I'm curious why the sensor hasn't flagged anything if they really are that low.
Interestingly, I double checked my invoice from the check... It says front brake pads on arrival were 5mm, but then at the bottom they need renewing as they're 1.6-3mm left... Perhaps this is why the sensor hasn't triggered anything
They did also state that the tyres I've had on for less than 1000 miles are all 50% worn as well...
Happy to be cautious and change them anyway, just interested about the sensor