Tower Bridge is pictured behind a fountain in central London.
As a safe haven for Russian billionaires, London has a lot to lose from mooted international sanctions against Russia over Ukraine -- which explains why the British government is being cautious.
The European Union and the United States have both threatened economic sanctions against Moscow for its intervention over the border, but while London has promised a strong response, it is particularly aware of the repercussions.
"There is a case that sanctions against Russia could in fact hurt London and as such, the UK, with London being the heartbeat of the UK economy," said Joshua Raymond, an analyst with City Index.
He noted that a "huge amount of Russian assets lie in the UK," whether in banks in the City of London or in property.
So many wealthy Russian individuals have set up home in the British capital that it has been dubbed 'Londongrad'.
Such is the scale of the invasion that it has inspired a reality television programme, "Meet the Russians", featuring surgically enhanced women with strong Slavic accents spending their cash liberally in London's shops and restaurants.
Some 70 Russian companies are listed on the London Stock Exchange, from energy giants Gazprom, Rosneft and Lukoil to the mobile phone operator MegaFon and Russia's largest credit institution, Sberbank.
Russians have also bought luxury homes in the upmarket London districts of Kensington and Chelsea, and Chelsea football club is owned by oligarch Roman Abramovich.
According to a recent study by private jet company Beechcraft Corporation, Russians spent more than £536 million (653 million euros, $896 million) on 264 homes in London last year, more than any other foreign nationality.
"If these assets are frozen and Russians cannot buy into London properties, one of the sources of London's price bubble will be taken away, putting property prices in London at risk" -- and with it, Britain's fragile economic recovery, warned Raymond.
Safeguarding the City
Some Russians in London are exiles who have fallen out with President Vladimir Putin. But the majority are simply keen to invest their wealth and spend it in the designer stores of Bond Street and Knightsbridge.
Russians are also increasingly paying into the British economy fees for some of the most elite schools.
The Independent Schools Council says 2,150 Russian pupils were boarding in private schools in Britain last year, paying fees averaging £27,600 a year.
Prime Minister David Cameron's government has publicly said that it is open to all diplomatic and economic options to punish Russia for its aggression in Ukraine.
But a document emerged this week making clear that ministers are concerned about the potential risks to the City of London's financial interests.
A briefing note photographed as it was carried into a meeting at Cameron's Downing Street office apparently recommended that "the UK should not support for now trade sanctions... or close London's financial centre to Russians".
Ishaq Siddiqi, analyst with ETX Capital, said the government was right to be cautious. "They need to safeguard the property market, they need to safeguard the City in any way," he said.
EU leaders are expected to discuss the issue of sanctions at a Brussels meeting on Thursday, while the United States has also threatened to punish Russia economically.
If there is no deal on sanctions, and the instability in Ukraine and Russia continues, London's reputation as a safe haven for capital could bring even more benefits.
"There's quite a lot of money flying out of Russia," said Siddiqi, noting the falling value of the ruble, accelerated by the events of recent days.
The London property market remains an obvious destination because "a lot of Russians see London as the next big global city after Moscow," and he predicts prices will keep rising.
New research from high-end estate agents Knight Frank found that 37 percent of the super-rich from Russia or its former republics intend to move countries. And their favoured destination? Britain.