I Initially thought these were going to be fitted 'just because I could', but actually they might turn out to be very useful.
First you replace the dust caps on the wheels with these:
Then plug this into the power socket
And there you have a reading of the tyre pressures (and the tyre
temperatures if you press the button on the side to switch displays).
Interestingly I had checked the pressures 2 days ago and they were all
reading 20 psi on my normal gauge which is just a bit above the
recommended pressure. As you can see, this system thinks they are 16
psi on the left and 15 psi on the right. So tomorrow I will to blow
them up a bit until I get 18 psi all round and see if it makes a
difference on my trip to the Great British Sportscars Open Day (free
coffee and cake ).