Miles Kington: Sat Nav can take you to the most interesting places

Sat Nav is short for Satellite Navigation. This is a system which gets you from A to B down a very narrow country lane (C) which is not quite as wide as your vehicle (D) with the result that you get stuck and arrive very late or not at all at B. The only way you are ever going to get yourself out is by enlisting the help of a local farmer (E) to pull you out with his tractor, and as he has only just returned home after rescuing the last Sat Nav casualty, it is (F) unlikely that he will feel much like turning out again just for you.

The first time I ever came across Sat Nav was when I was doing a talk at the Windsor Festival and they offered to send a chauffeur-driven car to wildest west Wiltshire to fetch me. At first I was hesitant about accepting such largesse, but they said that Honda, the sponsor of the Festival, would be very offended if I turned it down. And duly a limousine turned up in my neck of the woods, albeit a bit late. The flustered driver told me he had been taken by his Sat Nav through all the back lanes of Wiltshire, and one or two of the farm yards as well.

"I know the way to Windsor by heart," I said. "I can show it to you."

"I wish you would," he said.

Having a local to show you the way is the best system of navigation. Having a map is the next best. Using Sat Nav is the bottom of the pile. Our Ordnance Survey maps are so good that they are a positive pleasure to use, and even maps merely based on the OS are better than anything else – ever since I first encountered the brilliant Philip's Navigator Road Atlas (1 inches to the mile), driving in Britain has been a revelation for me.

(Yes, yes, I know that maps are not infallible. I once wrote a piece about the impossibility of finding Warwick University. A smug PR man wrote to me from Collins the publisher enclosing a free Collins Road Atlas, saying: "If you had had this, you would have been all right". I looked at the Collins Road Atlas. Warwick University was not on it...)

And all this brings me to last Tuesday when my brother Stewart and I drove north to near Shrewsbury for a family reunion. We divided the labour. He drove his trusty Volvo estate. I map read from my trusty Philips Navigator. Together we hit the A442 going north from Kidderminister and there, just beyond a village called Alveley, we saw an extraordinary sign at the entrance to a side road, saying: "Walk-on ferry only – (Sat-Nav error)". Not a hand-made sign. An official, all-metal road sign, firmly established out there by officialdom.

It was quite clear from the map what had happened. We were travelling parallel to the River Severn. For about 15 miles there were no bridges across the river. But some Sat Nav system had decided differently and had clearly been sending foolish customers down this lane to Hampton Loade to a non-existent bridge, presumably getting stuck and causing such chaos and fear and loathing among the locals that a signpost had eventually appeared commemorating the official incompetence of Sat Nav.

"It's worth a photo, I think," said Stewart, who had his camera with him.

"I think it is worth a piece," said I, who had my pen with me.

And that is how this brotherly photo-scoop appears in the paper today.