The Guardian suggests that Russian oligarchs used some legal loopholes to invest in UK, thus managing to secure some of their assets. The same article cites possible solutions for happening this in the future:
To expose, investigate and block the Kremlin’s money, we need three things, all of which are easily achievable if the political will can be found: proper transparency of shell companies, so we know who owns what; robust regulation of professional enablers, so crooked lawyers and accountants can be prosecuted; generous funding of law enforcement, so we can confiscate suspicious wealth.
Another Guardian article mentions that London Stock Exchange suspended a bunch of companies with strong ties to Russia. I guess that can count as better regulation of foreign investment, but I am not sure if this is temporary (i.e. until the Russian invasion ends) or not.
Has the UK taken any steps in the long-term for better regulating foreign investments?