British Airways run direct flights from London Heathrow to Moscow Domodedovo airport twice a week on Sunday and Wednesday. Total flight time is around 3 hours and 40 minutes.
Aeroflot is the Russian national airline and they run daily flights from London Heathrow to Moscow Sheremetyevo airport with the same flight duration of 3 hours and 40 minutes.
Aeroflot’s partner airline, Rossiya Airlines, are the only carriers offering a daily direct flight from London Heathrow to St. Petersburg Pulkovo airport. Total flight time is around 3 hours and 15 minutes.
Both cities have frequent connections with major European cities.
The time zone in both Moscow and St. Petersburg is GMT +3.