Oops,
there is some misunderstanding going round regarding police/PCSOs, powers & committing offences.
Police Community Support Officers are not volunteers. They are not police officers; they are civilians with different roles, responsibilities & powers though they sometimes overlap. They are fully trained employees of the local police authorities.
PCSOs do have powers which they can enact
without a police officer being present, for instance, they can direct traffic & pedestrians, they have the power to demand the name & address from anyone acting in an antisocial manner, they can confiscate alcohol & tobacco, they can issue fixed penalty tickets for some minor offences & they can seize vehicles from people using them anti-socially.
They can also detain people for up to 30 minutes until a Police officer arrives if they are suspected of committing an offence. you might call this a mini power of arrest.
It is not strictly true that you do not have to give your name & address unless you are taken into custody. If you are suspected of an offence which can be as minor as litter & you decline to give your name & address you will likely find yourself on a swift visit to the local nick while the police make enquiries as to your identity as they are entitled to do to anyone who cannot be dealt with by service of a summons, obviously without your ID they can't serve a summons & therefore can detain you for the purpose of dealing with the matter either by finding out your ID or taking you to court the next morning to be dealt with for the offence for which you've been stopped.
Whilst the regulations might say the officer should identify themselves to you this is generally only when they arrest you, a detained person is entitled to know the name & station of the person who is arresting them (though there are exceptions), if they are merely questioning you it is a matter for the officer whether they wish to divulge this info, in most cases you might say that to do so would just be polite, even if they don't this is not an 'offence' per se in the same way is it would be for, say a driver, refusing to give his name & address to an officer; Officers can be identified by their collar numbers & most forces now have name badges also. Oh, and they don't have to provide you with a pen & paper to write down their details (another often held misconception)
Regarding 'commercial licences' I think there is some misunderstanding here too. Commercial licences are required in just a few places, Trafalgar Square & Parliament Square in London are two, these are issued by Westminster Council, I believe who require commercial photography in those areas to be licenced, so they get some cash, they are required under local byelaw. People often think photography is restricted in these areas & this is not the case.
Save for certain military establishments, there is nothing to stop photography of public buildings from a public place. Security & other organisations may tell you that the building is copyright, however, whilst the plans may be copyright to save other architects from designing similar buildings, the image itself is not. The design, copyrights & patents Act has a section specifically exempting the reproduction of photographs of buildings from protection under the act, this also applies to works of art in public such as statues.
Where the confusion comes in is with model releases, or should I say building releases. This is where you take a photo of a building with the intent of selling the photos. A release merely protects the person publishing the image from being sued by the owners. It is not a legal requirement but you will have problems if you try to sell certain shots through image libraries who demand a building release to protect themselves once the image is published on their site & subsequently sold. It is not required to photograph the building. Should you make money from selling shots of buildings without permission it would be for the owner to sue you & may not be worth the risk if you are doing it commercially, if you're not then you have no worries.
This is my understanding.
you can read what the Met Police say about photography here:
http://www.met.police.uk/about/photography.htm