While Princess Anne drove, I told her all about my new self-driving car.

‘It’s amazing in multi-storey car parks’, I boasted. ‘It can even loop other vehicles when coming down the exit ramp’.

The only drawback that I had noticed so far was the car’s confusion when it entered a pedestrian zone. This happened to me in Birmingham city centre. Even the car’s specialist binoculars were of no use to help it navigate to a road.

Then I changed the subject to the Princess Royal’s hair. How long was it exactly?

The Princess shrugged off my enquiry, more concerned that there was an accident ahead. If we were held up in traffic, she would be sure to be recognised and then her safety compromised.