Understanding why even highly trained horses can bolt

Dr Gemma Pearson, the director of behaviour at the Horse Trust based at the Royal (Dick) School of Veterinary Studies, Edinburgh, said: “That is evolutionary. If a zebra sees a lion jump out, it will try to avoid it and the rest of the herd is likely to react in the same way and go in the same direction. That’s instinct rather than a horse actually thinking about it.”

I am not sure how often Army horses break loose in Hyde Park, but nine times out of 10 they will find their way home back home to the barracks – not to Whitechapel.

“They would normally go out of their way to stay together,” Dr Pearson added, “but if they go different sides of a bus you can see how they could get separated.”

Blood on a grey always looks infinitely worse than it does on a bay or brown horse because it shows up so dramatically, but my advice to anyone thinking of trying to stop a loose horse galloping at speed is don’t.

By all means catch one when it has come to a stop, but I once saw a Swiss trainer’s wife trying to stop her husband’s runner in the 1,000 Guineas before the race as it galloped loose round the track.

At the last second, she stepped out of its way, but the horse was thinking similarly and also took evasive action – in the same direction. It hit her like a steam train and no one wants that.