I have limited knowledge on helicopters as i am off to start my traing soon, but am a property developer and therefore can shed some light on noise regs and planning etc..., the following may may be of interest...
the doe have recently introduced a new building regulation called part e, this is to do with controlling noise etc in new dwellings.
If this chap has lodged a planning app for flats and a hotel they will have to be built to comply to part e, which means the developer will have to take into account the existing use of the heli pad and provide suitable sound insulation to the units. This is to protect the new residents and the existing commercial operations.
I would be most supprised if they were able to satisfy the new regs, and would therefore either, not get planning or have to close the heli pad so that it was not an issue...
My personal view on getting a consent for a new pad, is it would be almost imposible, current allowed levels of sound from new commercial sites, woorkshops, factorys etc is aprox 80db, a passing bus makes more than that!
The only chance would be on top of a tall building in central london.