Private security companies in England

I can tell you this - most are rubbish.

They cut costs where ever they can and hire anyone who can grunt out two words (Even if they don't actually form a sentence).
Most don't perform background checks on employees as they're desperate to get people who'll work long hours for lousy wages.
That means many criminals are employed in the industry.
The worst I saw with my own eyes was a kiddie fiddler arrested whilst working for a local company.
These companies will be less than willing to talk to you as they don;t want their places exposed for what they are.

You will be extremely lucky to find a company that will be willing to talk to you for the reasons mentioned in mas fred's post.

And unless you can find an individual with a grudge against his employer you will have no luck there either.

I have worked with  reputable security companies in Afghanistan and Sudan who employ only ex military personnel of the highest calibre. They will not divulge any information either as there is a confidentiality clause written into their contracts.

Thank you for the answers.

I'm looking for individuals that have hired the companies, not people who have worked for the companies (since this probably will be impossible). So if any one have any experiences with these companies (maybe have used their service in any way) I would like to get in contact with them.

I have tried to get in contact with neighborhood associations because they are dealing with these security issues and maybe some of them have been in contact with some security company. If you know any neighborhood association I would like to get the contact information.

Thank you