Back to seriousness for a sec. London is (as BBC Panarama uncovered recently) the money laundering capital of the world. With involvement of some of the worlds largest backs such as HSBC, Barclays and Lloyd's. It would not surprise me in the slightest if this has dirty money invested into it. Quite a good way to launder money, even with what they have done. We probably however, will never know. But filthy money is all over London in other investments, that is a fact. So why would it not pump into projects like this also?
The obvious answer being that if this was a massive money laundering operation and they got caught, anyone involved would be going to prison for a very long time. Unless you’re paying the solicitors off as well, it’s actually very difficult to launder money via property purchasing as the solicitors firm has a responsibility to comply with ML regulations and verify the source of that income - if they get it wrong (even if totally innocently) they would in all likelihood also end up in prison, if you haven’t paid them off and they realise then they have a legal duty to not only report the suspect, but not to in any way inform them that they are suspected, failure to comply with this (known as tipping off) is also likely to result in criminal sanctions.
Of course it goes on in large deals and it is possible but to suggest that any big project is likely to have dirty money in it is akin to suggesting any large wholesalers is selling cocaine on the sly.