If it is considered private property and he is told be one of his superiors that you aren't allowed there, then I would hazard a guess that he does know the rules.
I would hazard a guess, that they are clueless.
An official response found on a flickr discussion:
"Following the experiences of people here and people I know personally, whilst taking photos at Canary Wharf, I contacted the management at Canary Wharf about this, and received the following reply which may be of interest to people here:
"I am responsible for security on the Canary Wharf Estate and am extremely concerned at your suggestions of 'hassle' and 'assault'. You are correct in your assumption that the Estate is private property, to which members of the public are generally permitted access. There are numerous signs throughout the complex, advising of the fact that the Estate is private property and not a public right of way. That said, Canary Wharf Group welcomes visitors, whether they be workers, shoppers, tourists or photographers, but obviously retains the right, under civil law, to question and, if necessary, eject, individuals suspected of criminal, anti-social or prohibited activity.
Photography is not banned on the Estate and therefore there are no signs advising of its prohibition. However, professional photography is only permitted with our permission and when granted, a permit is issued.
Amateur photography is welcomed but, in the light of the current extremely high threat from terrorism, photographers may be questioned by security staff. Once satisfied with their legitimacy, security personnel will permit the photography to continue and I am very disappointed at your comments about the threats to confiscate the memory card or delete the photos.
Whilst I have, in the past, received a small number of queries regarding the questioning of visitors to the Estate by security personnel, this is the first time that I have heard of threats. If you can give me specific occurrences, I will investigate.
The Metropolitan Police are fully aware of our activities, aimed at combating the threat from terrorism and, provided that my staff are polite and provide an explanation for their actions, are comfortable with our approach.
I acknowledge that photographers are more likely to be challenged at Canary Wharf than in many other areas of London, if only because there are private security personnel on the Estate. I have to find the balance between providing a welcoming environment and also ensuring safety and security and it is extremely difficult to satisfy everybody.
Please be assured that there is no intention to hassle or assault and I regret if you or your acquaintances feel that to be the case."
I have asked for more clarification, particularly on how his staff define "professional photography". Any further responses shall be posted back."