I HAVE difficulty judging how quickly people are walking. This is possibly why I was never very good at football or three-legged races.

I think the first time I realised my limitation in this department was when I was assaulted by an elderly blind woman.

I was walking along a road, with a pavement of decent width, when the little old lady hoved into view, swinging her long white stick. As a result, I went into full blind-person-coming-readiness.

Now, as I walked I noticed there was a lamp-post ahead, and a car illegally parked with its nearside wheels on the pavement, leaving a very small gap. I’ve a certain degree of sympathy with the driver, as it was a narrow road, and I absolve him of blame for the incident which was to occur.

The blind old lady was approaching at, I assumed, normal blind old lady speed, sweeping her cane ahead of her. I was confident that I would reach the lamp-post before her and could nip around it, enabling both of us to go on our way. After all, I’m reasonably spry, and, crucially, sighted.

How wrong I was. The little old blind lady was walking at least as fast as me. She reached the lamp-post before me, blocking my path with the sweep of her cane and I had to fling myself into the small gap between the parked car and the post, grazing my elbow on it.

She, of course, was unaware of the distress she had caused and continued on her speedy way, scattering chickens and small children who ventured into her path.

But my inability to judge the velocity of pedestrians is now seriously inconveniencing other people. And I have now reached the nadir in my relationship with the rest of the human race as a result of it.

I held a door open for a lady. I often do this, I do it for gentlemen as well. I am an equal-opportunity door-holder, well brought up. Occasionally people even thank me for performing this task. This lady did not.

You see, when I opened the door, the lady (we’ll call her Lady A) was marginally in The Zone. That’s the area around the door within which one can expect the person by the door to keep it open until one arrives.

She was a middle-aged lady, and it’s usually fun holding a door for middle-aged ladies as they feel obliged to run in that way that only middle-aged ladies run – biceps pressed against their sides, forearms flailing, a face which says: “No, I am not running. Stop looking at me.”

But what I hadn’t noticed was that Lady A was walking very slowly indeed – limping, in fact. And now she felt obliged to pick up the pace because I was holding the door for her. Very, and obviously, painfully, she sped up, a brave smile on her face, flickering into a grimace every time she put her left foot on the ground. I could tell she hated me.

And I hated her a little bit, too, because the door was alarmed. We had around 30 seconds’ grace before the alarm sounded. “Come on, you slow moo,” I thought in my head.

Then she dropped a folder, and bent agonisingly slowly to pick it up. A dilemma – should I help her, or stay holding the door? I made a judgment call and stayed with the door – we’d both been through too much to throw it away.

Finally, Lady A came within range of the door, and I stepped back into the office. We were home and dry.

Except . . . the thing about doors is they have two sides. And if they have two sides, they have two Zones.

Behind me, rushing for the door was another woman, Lady B, fleeter of foot, who assumed I was holding the door open for her.

She dashed past me. I couldn’t stop her. I even heard her say, “Thank you.”

She crashed right into Lady A, almost knocking her on to her backside. And so, a sadder and wiser man, to the sound of the alarm, I walked away.

I couldn’t tell you how quickly, though.