Can the UK afford to extend sanctions to financial ones as a response to latest ex-spy's murder?

Question

Britain expelled 23 Russian diplomats over ex-spy’s poisoning. Most probably, this will be followed by a symmetric action from the Russian side.

Assuming that the UK considers issuing more consistent sanctions (e.g. financial sanctions), I am wondering if it can afford to issue such sanction, since the Russians seem to have a significant financial influence in London:

Russian wealth has permeated the upper reaches of society in Britain more completely than in any other Western country. The amount of money that post-Soviet oligarchs have pumped into “Londongrad” means, say critics, that David Cameron’s government will never crack down on them, no matter how incensed it is by Russia’s enormities. Accidentally revealed briefing notes stating that London’s financial centre, the City, should not be closed to Russians seemed to bolster the case.

Question: Can the UK afford to extend sanctions to financial ones as a response to the latest ex-spy's murder?

By "afford" I mean that the UK's financial loss will be greater that the loss inflicted on Russia.

Answer 1

Question: Can the UK afford to extend sanctions to financial ones as a response to the latest ex-spy's murder?

By "afford" I mean that the UK's financial loss will be greater that the loss inflicted on Russia.

Yes, but your question misses an important point, which is that the UK will not be doing this alone. It would do so by persuading its allies to impose economic sanctions as well.

Indeed, the Financial Times reported in August of 2018 that the UK had urged the EU to impose sanctions on Russia of the Skripal case. In the article (link via Google), the following is said:

The EU has had economic sanctions in force against Russia since 2014 over the annexation of Crimea. Any additional EU sanctions would require unanimous support from national governments to take effect. As an EU member, the UK cannot unilaterally impose sanctions.

The UK already successfully used this approach to get the US on-board, according to the BBC (August 2018):

The Russian rouble has slumped to its lowest level since November 2016, hours after the US announced new sanctions because of the poisoning of an ex-Russian spy and his daughter in the UK.

It should be noted though that US sanctions haven't yet been imposed, at least according NBC news reporting in January of 2019:

Nearly three months after deeming Russia in violation of a chemical weapons law, the Trump administration has yet to impose tough new sanctions on Moscow required by the law and triggered by the poisoning last year of former Russian spy Sergei Skripal.

Neither the BBC article or NBC News call them economic sanctions, but both referenced economics. The BBC referred to the Rouble going down and the previously linked NBC News article had the following on economic impact:

The nonpartisan Congressional Research Service in a report last month said that the second wave of sanctions "could have a negative impact on the Russian economy" but that the exact impact is difficult to predict — in part because of the possibility that Russia is currently planning ways to minimize the impact.