Why walk around London for 2 hours and spot only around 30 cars or so if you can spot close to 50 in 30 min. while in Dubai? If someone would actually spend 2 hours walking the garages and VIP valet parking in Dubai Mall I reckon you would be able to get something like 100-130 luxury/ sports cars together.
So, my advise, instead of London, come to Dubai if you don't have much time... ;-)
http://www.facebook.com/pages/Patrick333l.supercars
http://instagram.com/patrick3331
http://www.autog