We quickly arrived at a key juncture. Up ahead, the crowd streaming towards us away from the station; to my right, Shepherd's Bush Green and various people retreating from us; to my left, a side-street, Caxton Road. 

PC Lightning Strike waited on my lead. I tried to focus, to think, to recall some deeply submerged Jason Bourne-type muscle-memory. Which way would I go? I'd get off the main road, surely. But across the Green I couldn't make out anyone who looked like the man. So instead I spun round and squinted down Caxton Road. Where I saw two men walking away with their backs to us. And one wore a bomber jacket I vaguely recognised. It was enough to go on.  

As we headed down the side-street, the first man peeled off left into a pink housing block before the second man swivelled round and, catching sight of my fluorescent friend, suddenly made a run for it.

Now we're both in pursuit. But PC Lightning Strike is not the competitor he once was, so I soon led the pack. 

By now our man has turned into another street and exited frame. Arriving there well ahead of my now-struggling colleague, I decide to follow him.

Rounding the corner brings into view the surprising sight of the fugitive not speeding away but rather sprawled out on the kerb, having tripped himself up. 

Resisting the urge to rush into round two, this time I keep my distance, waiting around as in some Road Runner cartoon, holding out for back-up. Who eventually arrives, panting heavily between pronouncements, and proceeds to read our man his rights.

It is now that our culprit decides to take his assault-tally to three. He lashes out, throwing a punch at PC Lightning Strike.

I watch as the two heavies struggle in what seems like slow-motion.

"Take your hand away from your pocket!" was, I felt, my cue to re-enter the fray. Sharing my colleague's fear of a knife, I grab the man's jacket and try to pull it off as PC Lightning Strike holds                          down his "base", and our foe contorts his body like a toddler in a tantrum. 

We manage to strip him of his jacket but our success only spurs him on. Somehow, he slips free of the officer's grasp and is almost up and away. I can't bear it: I jump on his back and tackle him to the ground, managing, as he falls, to catch my hand between his body and the pavement. 

As I hold him to the floor, my fellow-musketeer finally manages to manacle the man. And then, at last: sirens, van, more policemen. 

As I hang around in the light rain to give my contact details-I am now unforgivably late for supper-my abiding thoughts are ones of self-doubt. As the prisoner sits cross-legged drunkenly wailing, and cursing me in particular, I wonder whether maybe I had escalated the situation. Maybe I had simply misinterpreted how people from beyond the Adriatic choose to express affection? Maybe I was butting my nose into other people's business?