I psoted recently on a web forum for PCSOs, and this was the response to photography in public:
"You're free to take photographs and if directed to do otherwise, just ask for the legal power or Act and Section from which the PC or PCSO believes they derive their power."
"I'm not 100% sure what powers of seizure PCSOs have nowadays - but I know that PCs would not necessarily need a search warrant to seize your equipent in some circumstances; if you look up Section 19 of Police and Criminal Evidence Act, you'll see that the powers to seize items is quite far ranging.
I'm pretty sure that S.19 PACE doesn't apply to CSOs though"
"Unless criminal enquiries or terror related, then NO right to confiscater or delete any pictures, whatsoever. However it doesn't stop you asking to see the pictures to determine for yourself. We get these very day on the railway and airports. Also no right to ask someone to stop filiming you in public ( railway stations are all private property and as long as it's not for commercial gain, selling to the papers or a mag, photoshoot etc, ) then it's not illegal, bearing in mind parents don't like their kids being filmed, especially at swimming pools and parks."
I'm going to carry on taking photographs, and take the proffered advice if stopped - after all the quotes above are from PCSOs, (two from the Met area and one from South London.)