I am tracking a tourist bus through the mean streets of Stoke, and I expect you are wondering how I'm getting on. I have made a particular study of buses, as you would imagine from someone in my position. I have familiarised myself with every aspect of them, and can identify them from the tiniest clues - a whiff of exhaust fumes, a fleck of paint, the taste of rubber left by a screeching tyre. So, shuffling along on my hands and knees, my nose pressed firmly to the tarmac, I was having no difficulty in following the trail.
I was slightly annoyed by people shouting at me to get out of the road, the honking traffic and so on. And the fag ends, sticky chewing gum and doggy do with which I was gradually getting coated was becoming unpleasant. But I did my best to ignore these unpleasant distractions and was making significant progress when I was stopped by a policeman. He motioned to me to pull over to the side of the road, so I grudgingly shuffled over into the gutter, where all the muck and doggy do was even worse.
"Evening sir," he says to me. "What do you think you is doing?"
I told him that I was trying to catch a bus.
He didn't like that and walloped me with his truncheon. "Very funny, sir," he says to me. "May I ask why you were in the road on your hands and knees, and not in a vehicle like other road users?"
I explained that if I had a vehicle I wouldn't be trying to catch a bus, which I thought was witty. He didn't and walloped me with his truncheon again.
"Can I ask if you have a licence for those knees?" was what he asked me next.
I said that I didn't think you had to have a licence for knees, and he explained that you do if you want to use them on the Queen's highway, then he walloped me again and arrested me for being illegally parked.