There are now 150,000 Russian expats living in London – and the crisis in Crimea is forcing them to take sides between east and west. Viv Groskop asks the residents of Moscow-on-Thames what the Motherland means to them

"There are two sides to this story. And they are both right," Galina Pentecost sighs. "People like clean-cut, easy-to-follow narratives. This isn't one." Born and raised in Yakutsk, in the remote east of Russia, she takes a pragmatic view of the Ukrainian situation. I see the Russian side. And I understand their position in thinking Crimea belongs to them. But I also see the Ukrainian side.

Pentecost has lived in southwest London for 12 years and has Russian, British and Canadian passports. "I do feel Russian, especially now," she says. A recent graduate of the London Business School's Executive MBA programme, she is chief financial officer for an internet start-up. "Having lived outside Russia for so long, I don't feel entangled in all the patriotism. But I'm careful about what I say and who I talk to, because I know how sensitive it is."

It's not an easy time to be a Russian abroad. Is this the time to remember your roots and explain the situation? Or to distance yourself? And what is the "insider-seeing-it-from-the-outside" perspective on Russia's prospects? Pentecost's cautious attitude is typical among the large community of Russians living in London. This isn't necessarily their fight. But as most were born in the USSR, it's a fight they understand inside out.

What was her reaction when she heard about Ukraine? "The first thing I thought: the rouble is going down and it will affect my parents' savings." They still live in Yakutsk. "If you have investments in Russia, it will affect you. But otherwise I don't think the relationship between Russia and London is altered. Most of the Russians who live here are professionals in their own right. They're like Europeans. They're international citizens."

Over the past 20 years so called Moscow-on-Thames has become home to an estimated 150,000 Russians. As Pentecost suggests, it's a difficult community to categorise, partly because "the Russians" have become almost as large a group as "the French" or "the Americans" in London. But also largely because what we understand by the label "Russians in London" has increasingly centred on a handful of wealthy individuals who own apartment blocks within stumbling distance of Harrods and lunch on "herring under a fur coat" (a favourite Russian salad) and sweet cherry dumplings at Mari Vanna, a glamorous Knightsbridge restaurant.

Last year Meet the Russians, the fly-on-the-wall documentary for Fox TV, took this idea to its extreme. It featured a pop star who bathed in champagne to improve her skin, had the walls of her home papered with gold silk and hired a French maid to wheel her pedigree puppies around in a pram. To peg her as "your average London Russian" is like believing that the cast of Made in Chelsea are typical Brits.

The "investor visa scheme" (where you invest £1m in government gilts in return for residency) has been extended to 433 Russian millionaires since it was first introduced in 2008. The effect of their spending power has given them extraordinary significance. According to estate agent Knight Frank, last year Russians were the biggest foreign buyers of homes in London, spending in excess of £500m. In reality when they say "Russians" here, they mean several high-rolling individuals.

There are no London-based names on the EU list of 33 Russian and Ukrainian politically connected individuals who are subject to a travel ban and an asset freeze. However, the political activist Alexei Navalny, a critic of Putin, has called for action against Roman Abramovich, the Chelsea FC owner, and Alisher Usmanov, a major shareholder in Arsenal FC. And Dr Andrew Foxall, director of the Russian Studies Center at the Henry Jackson Society think tank, has argued that "the oligarchs are Putin's soft underbelly."

Roman Abramovich has been targeted – ‘the oligarchs are Putin’s soft underbelly’. Photograph: Andy Rain/EPA

Others think targeting them is pointless. The newspaper magnate Alexander Lebedev said last week that financial sanctions would make no difference to Russian money flowing into London anyway: "British sanctions could not stop Russian kleptocracy from putting money here." Restaurateur Arkady Novikov was similarly undaunted: "I do not think much about these sanctions. I am not a little girl to feel offended by them. Tensions will disappear, business will remain."

Seeing beyond "Chelski" and the oligarchs, and gaining some real insight into Russia might be one unexpected side effect of the crisis, says Pentecost. "I left Russia long before the rise and proliferation of the oligarchs. In general I get a sense that people over here are intelligent enough to know that a few individuals cannot represent and influence a stereotype of a whole nation."

In fact owners of puppies-in-prams make up far less than 0.5% of Russians in London. London is also an increasing focus for middle-class Russians, both as a place to live and a place to visit. Shopping and tourism company Global Blue reported that Russian spending in the UK dropped by 17% as the value of the rouble fell since the Ukrainian crisis. And then there are the financial links between our two capitals, although some now consider that Russia's role in London's business world has been overstated. Think tank Open Europe points out that only 1% of the UK's financial services are exported to Russia, compared with 6% to Switzerland and 28% to the EU.

Pentecost is more similar in profile to most Russian Londoners in that she came to the west with nothing and is self-made (and, despite having great skin, does not bathe in Dom Pérignon). She was transferred to Canada where she trained as an accountant, after she got a job with "the only foreign company in my town" in the late 1990s. "The main reason I left Russia is that the life there sucked, especially in Yakutsk," she says. "The weather alone was hard to deal with. It is -40C for three months straight, plus a month of -50C. I grew out of the place quickly and wanted to explore the world and make a better life for myself and my family. My two brothers followed me to Canada and they both live there now."

Most of the Russians living in London have been here for a long time and feel almost British, although they hate the suggestion that they've lost their connection to the homeland. And this conflict brings that all back. The idea of rodina – homeland – is central to being Russian. That's not easy to square for expats.

Anatasia Webster photographed at Pushkin House, London. Photograph: Suki Dhanda for the Observer

Long-term resident Anastasia Webster says: "When people ask me, 'Do you think in Russian or English?' I know the answer is most probably English, but I do absolutely feel Russian." Married for 15 years to jewellery designer Stephen Webster (she's also the company's international marketing director), Webster left St Petersburg at 18 when she found out she had relatives in the US.

The current situation is a reminder of her roots, though. She feels as if she has seen something similar before. "My father was a scientist at a big centre in Latvia. His colleagues had to pack their bags and leave because they were ostracised. It became about nationalistic animosity. Our nannies [for her daughter] have always been lovely Russian ladies from the Baltic republics, teachers, doctors, who couldn't get a job at home because they were Russian."

"I don't have a problem with Crimea going back to Russia," she says. "People who live there don't want to be a part of Ukraine. The problem is, it has all been done too brutally and too quickly. I hope it won't become a wider issue, because this is a very specific territory and it's a specifically Russian territory. Putin has managed to make Russians feel that they're going back to becoming a world power. Since Russia fell apart [in the early 1990s], no-one cared about them any more. There's this issue of Russian pride."

For those who devote their lives to showcasing the more benign forms of Russian pride, though, the timing of the Ukrainian crisis couldn't be more awkward. Next week London Book Fair welcomes a large group of Russian authors and will be hosting several Russian-language events. More significantly, in early March the British Council announced that it was continuing with plans for this year's UK-Russia Year of Culture 2014, although it would be "monitoring the situation in Ukraine and Russia closely". This is a cultural exchange first floated by William Hague last year.

Vitali Vitaliev: ‘The basis of this conflict is a hypocrisy that’s lasted 70 years’. Photograph: Suki Dhanda for the Observer

In autumn the Science Museum will host Cosmonauts, an exhibition on the Russian space programme; from July the Tate Modern hosts the first British retrospective on avant-garde painter Kazimir Malevich in 25 years; and the Mariinsky Theatre's Valery Gergiev brings Wagner's Ring Cycle to the Birmingham Hippodrome in November. In return, we're sending the Russians drama from Shakespeare's Globe, dance from the Royal Ballet and nine remastered Hitchcock silent films.

"I can see that long-term the Ukraine situation is obviously not positive for the international image of Russia," says Nonna Materkova, originally from St Petersburg, now a London-based economist and philanthropist. She is the founder of Calvert 22 Foundation, a gallery with a focus on the former eastern bloc with an upcoming exhibition on Russia's rising photography stars. The gallery's events are part of the UK-Russia Year of Culture: "The situation is very disturbing not just for me but for all the team I work with, some of whom have Ukrainian backgrounds," she says. "Some British people do not understand that a large percentage of Russians have relatives who are Ukrainian."

She can also see an opportunity to educate, though. "Cultural relations become even more important in this situation. Politics is one thing but when people actually talk to each other, things are different. In our shows and events, we take a multidisciplinary approach to create a more complex picture, looking at the history and context. I don't think politics can cut all those creative links."

Promoting "the understanding of Russian culture" is the aim of Pushkin House in central London's Bloomsbury Square, established 60 years ago. The winner of this year's Pushkin House prize for non-fiction is announced on 30 April: it's telling that the six shortlisted books do not include any contemporary writing on the post-Soviet situation. (Full disclosure: I'm one of the judges.) But the aim of the prize is "to go beyond the stereotypes and short-term politics", says the House's co-chairman Andrew Jack, because suddenly the long view is everything. Galina Pentecost says she has just bought a book on the Crimean war "to try and understand the dynamics."

‘This guy is not going to back down. He wants the Soviet Union back?’: Putin arrives for a meeting at the Kremlin. Photograph: Alexey Druzhinin/Getty

This is where Russians seem most conflicted: feeling part of the situation but at the same time feeling distant and powerless. For others, this is an opportunity to feel more European and rooted here. The writer and broadcaster Vitali Vitaliev, who first made his name here as a defector in the early 1990s on TV's Saturday Night Clive (with Clive James), embodies the identity politics at work. Vitaliev was born in Kharkov in eastern Ukraine, went to a Russian-speaking school but also learnt to speak Ukrainian ("although it was optional"), was fluent in English from the age of 12, has lived in the West for two and a half decades and has British and Australian passports. He now lives in the place he proudly calls "Letchworth Garden City".

"I never felt Russian or Ukrainian," he says, "When people ask me what I feel… I feel European. I lived in Moscow for 15 years, but I have never been to Russia. I have only ever been to the Soviet Union," he laughs. This is a joke. But it's also true. And it's part of the current conflict: this is about resolving the identity gap left when you don't have to be Soviet any more.

"The basis of this conflict is a hypocrisy that lasted for more than 70 years," he explains, "When I was at university, all subjects were in Russian, except for Ukrainian literature and language. We had a couple of guys who were reading [the 19th-century Ukrainian poet] Shevchenko and started talking in Ukrainian amongst themselves, which was very unusual. They were expelled for 'Ukrainian bourgeois nationalism.' I'm still not sure what was bourgeois about speaking their own language in their own country. It was complete idiocy."

But even the most basic of conversations with "Russians" reveals how complex their concept of identity is. It's not about where you were born or where you live now. It's about how you feel. Alexander Kan, arts and culture correspondent for the Europe Hub at the BBC World Service, is originally from Kherson, near Odessa in southern Ukraine, and has worked in London for 18 years. "I would probably speak of myself as a Russian Jew," he says. "Culturally and linguistically I am much more part of Russian culture than Ukrainian. I feel torn apart. It is a line I would draw from the top of my head to the floor. You ask what the West does not understand about this situation. It is this: when Russian propagandists and Putin say this is one nation, they are not far from the truth. If you take the conflict between the Serbs and the Croats as an example. They spoke one language and had lived for many years next to each other not quite knowing who was Serb and who was Croat. But there was a fundamental religious difference. Here, we don't even have that as a difference."

What next, then? Vitali Vitaliev says: "I am an optimist. But some people are talking about world war three. If you remember how the previous world wars started, it was from much smaller incidents. This guy [Putin] is not going to back down. He is saying it every day. He wants the Soviet Union back. It cannot be brought back. But he wants it back. So what do you do?"

"Putin is not a stupid man," says Galina Pentecost. "He knew what he could get away with. If this were a game of chess, you could say that he's already won." This is the other common factor among Russian attitudes, even abroad. Although most regard him as authoritarian, no one questions Putin. As one Russian friend once said to me, "Putin is a fact. Why would you question a fact?"