OP, why don't you try to get in touch with Stefan Katafai. Seems he is in direct contact with 300 billionaires.
His website has a phone number and email address: http://www.agent4stars.com/
I think you should highlight the proximity to the Prime Minister's residence.

Edit:
OP, another option. Trump International Realty. Contact them here: http://www.trumpinternationalrealty.com/contact/
Who knows, Donald Trump might buy for himself. 

*starts dreaming about his $200,000 bounty*