Due caution needs to be exercised with regard to minimum separation when operating in such circumstances, Chopjock.
Whenever I've been obliged to gain a CAA written permission in circumstances like this (I've kept a box file of these from the past obtained when I've been required to land at a hotel or other location in a congested area), as I'm sure you have, they have always stipulated a minimum separation distance, usually 30 meters, sometimes more - without going through them all I know it reads a rather surprising 100 metres on one of them - iirc, that was at a hotel helipad near LHR.
I recall a court case from a few years ago where a woman claimed to have been blown off her chair and injured by a helicopter hovering at a hotel. The allegation was upheld.