I HAD to catch the bus for a meeting and it was warm, early July warm. And I don’t mean normal early July warm, where we are insulated by off-white clouds and the rain is slightly less cold.

No, I mean this early July warm, where the sky is an unbroken blue and the grass verges are an unbroken yellow, where the tumbleweed blows across the cracked soil and tongues dart in and out of the mouths of lizards.

I do not know if you have ever been on a bus in such weather, but it is like a greenhouse on wheels, a portable Tenko, a charabanc outing for the Body Odour Pride Support Group.

Windows are abundant, and windows that can open are rationed, because it’s a nicer design, and air conditioning is restricted to the breeze caused when somebody rushes past when he realises that the bell didn’t work and he has to alert the driver to his stop sharpish.

And I was wearing a dark suit and trying not to perspire, in circumstances expressly designed to make a body perspire, because I was going to a meeting and did not want to give the impression that I had stopped off at the baths in order to dive for a rubber brick.

“Think cool thoughts, chum,” I told myself. I imagined Rihanna and the late Sir David (Aptly-Named) Frost sitting on thrones of ice while making short work of a pile of strawberry mivvis, and, for a moment, this inspirational scene fooled my easily-led body into holding off on the sprinkler system.

“This is good,” I thought. “The important thing is that nothing enrages me in the next five minutes…”

And then I saw him. Across the aisle, there was a man, also dressed in a dark suit, the sweat on his neck making his hair curl. Had things turned out differently, I might have shared the Rihanna/Frost secret with him and changed his life.

But they did not. I saw him reach into a carrier bag and bring out a cheese sandwich. And instead of him saying to the rest of the passengers, “Who has put this in my bag? I mean, what sort of absolute psycho eats a cheese sandwich on a bus as hot as the core of the sun?” this man actually took a bite of the sandwich.

I do not want you to think I am against cheese sandwiches in general. There is little that gives me greater pleasure than Cheshire cheese and tomato on some thickly sliced wholemeal bread. And I am a big fan of the cheese toastie.

But it is utterly unacceptable to attempt to make a cheese toastie by using the heat of an early July bus, no matter how hot it is.

Just imagine what this cheese sandwich would have been like – medium-sliced Mother’s Pride slowly drying out on the outside, butter melted into bubbling liquid, and cheese, sweaty and floppy. What kind of monster could actively enjoy that?

Reader, I baulked, involuntarily and loudly. I am sure I was not the only one.

Because you can’t do that. Cheese sandwiches are on the list of things you cannot eat on a hot bus, because of the effect they have on normal people like me. The other items include – and this is not a complete list – egg sandwiches, fish sandwiches (specifically tuna), sliced ham, slices of melon, peaches, and yoghurt.

And then he took another bite, and a small morsel of cheese attached itself to his chin. Did he not know, or did he not care? I expect it was the latter. Either way, it remained on his chin as he polished off the rest of his vile sandwich, as if he were taking part in some sort of Japanese gameshow.

I felt the heat rising in me throughout, and the sweat ran down my face and the back of my neck, and I turned up at my meeting looking as if I’d been sculpted out of strawberry ice cream.

Some of you – the worst of you – will be thinking, “Just get over yourself, Gary. He ate a cheese sandwich on a bus. What’s it got to do with you?”

But what if he’d been flossing his teeth, or cutting his toenails right in front of you – both examples of behaviour I have witnessed on the bus?

We have to draw the line somewhere. And this is where I draw it. No cheese sandwiches on hot buses.