Russia, says Theresa May, is a “hostile state”. Over the last few months Britain’s Prime Minister has ramped up the rhetoric against the regime of President Vladimir Putin.

She has called out Kremlin efforts to destabilise the West, including its propaganda and misinformation machinery, and its bullying of neighbouring countries.

And, despite Brexit, Mrs May has re-committed Britain to the European sanctions imposed on Russia after Mr Putin annexed the Ukrainian peninsula of Crimea in 2014.

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The Tory leader also says she wants “to tighten financial regimes to ensure the profits of corruption cannot flow from Russia into the UK”. This is where it gets tricky.

Britain may well talk tough on the Kremlin. But it is struggling to act tough on some of the regime favourites laundering the cash they loot from their country through the UK.

That is because Putin’s oligarch friends - and sometimes his enemies too - are exploiting Britain’s soft-touch business regime.

So much so that last year anti-corruption campaigners even ran “kleptocracy bus tours” of the London homes of Russia’s rich and famous. One in 10 properties in central London are owned by offshore firms.

There are lots of reasons rich Russians - and far from all of them are crooked - want to invest in Britain. One, ironically, is the rule of law.

After all, your stash is probably safer in Britain than in Russia. Your face may well fit in the Kremlin right now. That might change. And do not count on a Russian court to have your back. So you put your money in a London house. And then in to a Scottish limited partnership or SLP, the corporate vehicle dubbed “Britain’s home-grown secrecy vehicle”.

Mrs May is not to blame for the abuse of SLPs, many of whose owners effectively remain secret. Her government, after all, did not force Scottish and international lawyers and company creation agents to set such firms up and then host them for thousands of anonymous foreigners.

But company regulation is not devolved. So SLPs are Mrs May’s problem as much as London’s property market.

We know three-quarters of identified owners of SLPs are in the former Soviet Union. So if the prime minister is after Russian dirty money, this is a good place to start: the biggest money-laundering scheme ever exposed, the Russian Laundromat, used SLPs and other UK entities.

All these shell firms were registered at Companies House, Britain’s understaffed corporate registry.

There a tiny band of civil servants are expected to police four million corporate entities, including some 18,000 SLPs still to even begin to comply with new transparency rules. Their task is near impossible.

If Mrs May really wants to go after Putin regime cronies she could start getting her own Companies House in order first.

She would also be doing her own Exchequer a big favour. Because it is not just Russian money that is dirty. Plenty of British cash is too.