I was stopped once by the Thames in East London by a trio of PCSOs. I had my Mamiya 6 on a tripod and was waiting for late afternoon light over the river towards Canary Wharf. PCSO 1 enquires "Can I ask what you're doing sir?"
I resist the temptation to point out to the officer in question that her question ought correctly to have been phrased "May I ask what you're doing?" (or perhaps just "What are you doing?"). Instead I simply answer, "Sure. Ask away."
PCSO 1: "Er well. What are you doing?"
Me: "I'm taking photographs."
PCSO 1: "What of?"
Me: "The river."
PCSO 1 (gesturing towards Canary Wharf): "What about those buildings?"
Me: "Yep. Them too. They'll be in the photo."
PCSO 1: "Can I see the photos please sir?"
Me: "No. Afraid not. It's film you see."
The PCSOs then proceed to attempt to take my personal details. Naturally I refuse and remind them that while police officers are obliged to identify themselves to me, I am not obliged to identify myselves to police officers let alone mere PCSOs. At this stage, I make a point of taking the badge numbers of the 3 PCSOs and scribble them down in my notebook.
The three amigos trundle off slightly flummoxed by the situation. The light begins to change and I get some nice shots. Not long after, the trio returns, with two real police officers, handcuffs, batons and other accoutrements on display on their belts.
The first copper comes over to me and says, "I understand there's some trouble sir."
I explain that there's no trouble at all and that while I appreciated the need for vigilance, it should have been evident to the 3 PCSOs that I was a hobby photographer out enjoying the light rather than some nefarious terrorist plotter. I said that I thought their disturbing me was an uneccessary and unwarranted intrusion.
Thankfully, it took the copper in question about 5 seconds to agree with me. It was evident to anyone with a brain that there was really nothing suspicious about my activity. The copper apologises for the disturbace and all 5 wander off, leaving me to the light.
I had a similar experience walking through London Bridge station when I was randomly stopped and searched by a PCSO acting under supervision of real police officers. I allowed the PCSO to look in my rucksack. The PCSO gets his notebook out and asks for my details. I refuse. This really throws the PCSO, who insists that I need to give my personal details so he can fill out his form. I tell him that I really don't have to tell him who I am or where I live. He seeks advice from one of the supervising coppers who tells him to just take my description. The copper knew full well I didn't have to identify myself unless they intended to nick me for something.
These 2 experiences really annoyed me. London does feel like a police state sometimes. Even more annoying is the fact that vast swathes of what one would imagine to be public space is actually private property, where controls on phography can be quite legitimately imposed. I learned this recently beside St Pauls cathedral where there is a modernised courtyard shopping area owned by a private company whose security guards refuse to allow you to set up a tripod to photograph the cathedral from what would otherwise be a great spot.