Mike Byrne said in his letter that he is concerned he might one day have to present his ID card when buying petrol (Who picks up the ID trail? letters.computing.co.uk).

He need not worry – this is not necessary. At Birchhanger Green services on the M11 I observed a notice that all registration numbers are checked against the Police National Computer before the pump is enabled – and that this information will be retained. I suspect the “Time to next junction” signs on the M25 and others are also recording your number plate as you pass – it is the easiest way to produce the estimate.

Andy Champ