I know just what I want for Christmas – but I’m not sure it’s legal | Adrian Chiles

Wouldn't it be great to have an LED sign in the back window of your car to send messages to other drivers and put an end to waving and gesturing? Well, such a device exists

I know what I want for Christmas - an LED sign for the back window of my car. I've only just realised these things are readily available. I assumed otherwise because in all my years of motoring I've only ever seen one in operation. It was about six years ago on the A55 heading south towards Wrexham. I was riding my motorbike. It was a beautiful moment. A black Range Rover ahead of me was indicating a wish to move into my lane. I slowed down a little and nodded my helmet to signal my assent. And blow me down if an LED sign in the back window didn't flash up a cheery THANK YOU. So sweet. But then I felt a bit rotten because I had no way of returning this friendly fire when I overtook him. It felt impolite not to say NOT AT ALL! But it's difficult to physically communicate that, especially on a motorbike. With a random head movement and a slightly raised thumb, I did the best I could. All in all, it really was a most satisfactory exchange.

You get a lot of thinking time when you're riding a motorbike, so I came to wondering what he might have flashed up if I hadn't allowed him to pull in front of me. If he'd been disappointed enough to chase me down and get past me, what might have been his message? I thought of THANKS FOR NOTHING, or perhaps a simple FUCK YOU.

Adrian Chiles is a broadcaster, writer and Guardian columnist