As a Russian family living in London, when you think about your children's upbringing, why do you think that having a nanny from Russia is going to be the best for them?
Whether your move to London is Long term or just for a short time you still have to think about your child's development. While they are living and growing in a different part of the world it is important to keep a strong and close connection with their country.
You yourself have strong values that you want to impart on your children, to achieve this you have to be able to communicate the subtleties' of your values to someone who is going to fully understand and be able to reinforce the choices you make for your offspring.
When growing up amongst a different culture so far away from home, it becomes more important to teach your children about the Russian way of life. Simple things like having food cooked and nursery rhymes sung by someone from Russia means you know that they will taste a little bit of home.
Of course you want your child to speak proficiently in English this is why your nanny should be fully bilingual. Language skills will help your child excel with their education and in the future, business dealings. What is equally important is to make sure that your child speaks their mother tongue like a native speaker. Speaking with another native speaking Russian on a daily bases is essential to their development.
There are many reasons that you prefer your nanny to be from Russia, but in short you want your child to develop as part of your culture. This is a good thing to preserve, and in my opinion should be encouraged.