Nah, it has been widespread knowledge for decades now. When Roman Abramovich bought Chelsea FC in 2003, the phenomenon was already well-known. London has been Oligarch Central pretty much since the Eltsin days.
No, the real issue is that the UK government continues to struggle under public debt. Since 2010 they've cut every expense they can cut, so now they're trying to raise taxes. One of the avenues for new revenue (eh) is to close all the well-documented tax-code loopholes; and the most classic one is where you create Company X from a tax haven, make it buy property in London, then sell the whole company, bypassing all taxes that should be triggered by property sales. That's what this new law is really supposed to fight.
It's actually not a terrible idea, and I say that as someone who actively despises the current government. Obviously it will likely end up favouring the sort of old-money connections that the Tory party naturally represents, people who cannot hide their wealth because they've literally owned most of the country for centuries; but if it brings home some much-needed cash and stems a bit the relentless flow of dirty money that keeps London fat and arrogant, so be it.