I FLOPPED onto the seat on the bus. It had been a difficult boarding process.

I will explain. The bus terminus at Paradise Street, in Liverpool city centre, has automatic glass doors, which are triggered by the arrival of a bus.

Owing to an unlikely, but inevitable, series of events, my bus arrived, but did not attain the position from which the doors would be triggered. But this was fine as the doors were still open thanks to the recent departure of the previous bus, and people poured through the door and onto my bus.

I do not know if dawdling is going to be an Olympic event at Rio, but, if so, I would recommend to Team GB scouts the person who was just in front of me, boarding the bus as if his life very much did not depend on it.

As a consequence, the sliding doors closed in my face.

The bus driver stared stonily ahead as I and a couple of similarly cheesed-off passengers banged on the doors. He inched forward in order to pull away and the sliding doors began to open. I pushed through and knocked on his door. He turned and shrugged, his shrug saying, “It is not my fault you were too slow to get on my bus. Rules is rules,” and made to drive away.

I am a mild-mannered person, but even I have my limits. Apart from anything else, it should be “Rules ARE rules.” I bashed on the door one more time, then did the only thing a reasonable person could do.

I flashed my wallet at him, as if I were a gun-toting FBI man who had been chasing a fugitive through the streets of Brooklyn, and had been detained mistakenly by the local constabulary.

I reasoned that a man who took refuge in regulation would be cowed by somebody who looked official, and so it proved. He opened the doors and my fellow sufferers boarded the bus. One even thanked me. I felt like Eliot Ness, an upstanding man forced to use underhanded methods for the common good. Or Batman. Especially Batman.

I flopped onto my seat, as I believe I mentioned. At the next stop, a gaggle of pensioners boarded, as it was just before their bus passes ran out. Some appeared very frail, unnecessarily, in fact.

I stood up, and watched the gaggle of pensioners size each other up to decide which of them was most deserving of my seat, like a benevolent version of The Balloon Game.

And while they were deciding, a young woman got on the bus and sat in my seat.

My indignation levels were already up after the sliding doors incident, and I was ready to explain forcefully that the course of action she had just taken was sub-optimal with regard to common decency when it occurred to me that the woman in question was black. And that stopped me in my tracks.

I accept I was within my rights to point out to the woman the sign which reminds people that seats at the front are reserved for pensioners of the precise degree of lameness as those surrounding her at that moment.

But I am well aware of the cultural significance of telling a black woman to vacate her bus seat. This is how revolutions start. I was not going to be the man who told Rosa Parks to shift up to the back.

I was paralysed by my liberal values. So I stood and looked at her, hoping to convey to her, through the medium of facial expression, that her conduct was inappropriate. But I had no idea what facial expression I could use. I was trapped between anger, incomprehension, amusement and disappointment, but even more so than usual.

Then I gradually realised that what I was actually doing was staring at a young woman on the bus, and so I looked away, defeated. What would Batman do in this situation, I wondered?

But he wouldn’t have been on the bus, would he? He would have been in his Batmobile.

And, not for the first time in my life, I wished I had a Batmobile.