One punch.

Right hand.

Full force.

They don’t do it in the movies. But the heart is the very worst place to be hit hard. You really don’t want to get hit in the heart.

It was a punch that began in the pivoting sole of my left boot and travelled up the muscles in my left leg, gaining full momentum with my twisting torso and then racing down my right arm into the first two knuckles on my right fist.

Less than a second after it had begun its journey, the punch slammed with enormous force against the man’s sternum, right on the flat bone at the front of the chest where the upper ribs are attached by cartilage just in front of the heart.

I can never understand why nobody ever punches the heart. Drunks in a bar fight would not think of punching their opponent’s heart. Street fighters at closing time would never dream of hitting a man in his heart. The average yob, like these three very average yobs in Charterhouse Square, know nothing about a blow to the heart.

But I knew.

The heart is everything.

The weightlifter staggered backwards, his hands on his heart, reeling from the trauma of chest compression. He sat back down on the bench, between his dumb friends, the fight all out of him. The punch had collapsed his sternum maybe an inch, no more, but it was devastating enough to shock the heart.

I looked at the other two, their faces already frozen. They didn’t know what to do now. I didn’t expect them to. And I looked at the weightlifter, clutching his chest, pawing at his collapsed sternum, and I could see that he lacked the will to get back up.

It was more than just the shock of being punched in the heart. The punch had induced tachycardia – an abrupt and terrifying increase in the heart rate.

He felt like his heart was about to explode.

He felt like he was dying.

I walked back to my dog and rubbed his neck.

‘This is Stan,’ I told them. ‘Stan is a Cavalier King Charles Spaniel. Cavs are the most peace-loving dogs in the world. They are famous for being mild-mannered and polite. Great with children. They were the favourite dog of the Tudor and Stuart kings because of their gentle nature – the gentle nature that you can still see with Stan.’

‘We don’t want any trouble, man,’ one of them said.

I looked at him sharply. ‘Can you see Stan’s gentle nature or not?’

‘Yes,’ he said.

I needed coffee immediately. A triple espresso that you could stand your spoon up in. Stan gazed at me with bashful love. He would sit on my lap outside the café and I would drink the short black coffee while I fed him Nature’s Menu chicken treats until it was time to go to work.