That sounds very convincing, about the tire sensors --
so the dashboard light is in fact working fine,
just the sensors are off.

Presently I am driving the car with that light signal on the dashboard,
it does not switch off at higher speeds,
and if the car is stopped and started again, the signal lights up again.

This is probably a job for the service mechanic.
In the meantime the wheels and tires are as they ought to be.