David Mitchell showed me his DSLR camera and its a full range of lenses. It was then – two days into our two week holiday touring the Scottish highlands – that I realised that I only had the telephoto lens for my own camera. I had left everything else at home. Although it would be a pain, it was worth turning back 28 miles to return to Edinburgh the next day and collect the rest of my photography equipment. In any case, someone was needed to take my little sister’s friend back to town after a night away with my family, so I might as well do this at the same time.

The next morning we set off for the city by foot. Crossing the moorland riddled with ditches was very difficult. In some places the track disappeared completely, and in others it was replaced by rope ladders and zip wires.

At sea level we eventually reached a National Trust visitor centre. We walked past the main exhibition and into the street where we were greeted by one of the mothers of my little sister’s friends. She said that she could tell that we were desperate for a car, handed over a bunch of keys, and ran off into the distance.

From the keys in my hand it looked like I had a choice of a Lotus sports car, a mark 3 Ford Granada, and a Range Rover. All I needed to do now is identify from the row of parked cars one that matched a key, and then we’d soon be on our way. This was not as easy as it seemed – there were far too many cars to check – and I soon realised that I needed to recruit some help. I identified a group of my little sister’s friends and bent down to talk to them.

I’d barely spent two minutes with the children when a busybody raced up to us and hauled me away from them. When I explained what I was doing she declared that this was just the kind of evidence to prove that I was a child abductor. I rejected this as ridiculous, adding that I was a university professor. “Even better” she replied “I can’t wait to see how the Sun will use that information in the headline when you are convicted”. With this she marched me off to the police station.