'I noticed a police officer on the other side of the street, crouching down and partly obscured by a tree… He slowly approached me, and I realised he had a gun'

I'd been doing the same training walk for several weeks, twice a day, six days a week, on a quiet residential street near where I live in Oxford. I'd chosen it because it had a steep hill, perfect for a good workout and, as always, I was wearing my weighted exercise vest. Black and rectangular, it straps across your chest with pockets for the weights to build muscle. Because I'm used to being around other people with the same interest, it never occurred to me that it might look odd.

In retrospect, I'd had the occasional double take, but my training times are so regular I'd pass the same people every day. Normally I walk up and down the street five times, which takes about an hour. That afternoon I'd been up and down twice, and was just starting down the hill again when I noticed a police officer on the other side of the street, crouching down and partly obscured by a tree. He wasn't dressed in the usual uniform – instead of a standard jacket, he was wearing a bulky vest. This struck me as unusual, but I didn't loiter. As I continued, though, I realised he was pointing at me, and appeared to be saying something.

I had my headphones on – I'm a PhD student at University College, and usually listen to a lecture while training. It was only when I removed them I heard him shouting, "Stop! Stop! Put your hands up in the air!" I couldn't fathom what the problem was but I did as he said, automatically taking one or two steps forward as I raised my hands. "Don't move, don't move!" the officer shouted. He slowly approached me, and I realised he had a gun.

As he drew close, the policeman started examining my vest, and tried to take it off – he couldn't work out how, so I had to lower my arms to help him. Another armed policeman appeared, and started to examine the vest on the ground as his colleague questioned me.

"What are you doing here?" he asked, in a severe tone. "What is this vest?" As I explained my training routine, the other policeman searched me, apparently for hidden weapons. "Do you realise what this looks like, given your appearance?" asked the officer. "We had a call from someone saying they'd seen a suspicious man. We were told he might be wearing a bomb suit."

This seemed pretty odd to me – I'd never seen a bomb suit, but I was certain they wouldn't be emblazoned with a "Maxivest" logo. I was more surprised by what happened next, though. "We need to do a background check on you," said the policeman. He told me that under the Terrorism Act, they were entitled to take me to the station for further questioning, and that they needed my details to ensure I wasn't already known by intelligence agencies.

Now my bemusement turned to indignation. We'd established I was a student, that the vest was a piece of training equipment and that I was no terrorist – that even if I'd been attempting some kind of prank, I'd have been making a poor job of it. It was only then I realised the possible significance of his earlier remark – "...someone of your appearance..." Although I grew up in the Netherlands, my parents are Iranian – did he mean my Middle Eastern looks made me more suspicious? Never feeling restricted in my freedom of movement before, it was a possibility that genuinely hadn't occurred to me.

After about 20 minutes, I was allowed to go on my way. But I hadn't finished my training, so at the end of the street I turned and walked back again, passing the police car with the officer in it. "You're still walking?" he asked. "Why don't you call it a day?" I explained I wanted to continue with my training, but he ordered me to take off my vest. I pointed out it wouldn't be feasible for me to walk with it in my hands – it weighs 30kg – but he insisted, sharply. Not wishing to provoke him, I agreed to cover the vest with my jacket. I walked away looking ridiculously bulky, and probably more suspicious than I would have otherwise.

I still train twice a day, on the same street, and don't make any attempt to cover up the vest. I'd have appreciated the opportunity to meet with whoever raised the alarm, to explain what I was really doing. It seems everyone I pass knows who I am now, but rather than react with fear and suspicion, people wave and smile.

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