It is indeed a carriage from one of the Russian underground systems. I vaguely recall having seen this story sometime ago, and back then it was reported that this guy was spotted in Moscow underground, but these kinds of carriages can be seen in Moscow, St. Petersburg, Kiev and possibly other cities.
That metal pole should be coloured (dark blue, dark red, or yellow) if it were a London Underground train. I even Google Image Searched it, and cannot find a train that looks like that. Plus the shape of the pole is all wrong...
and was posted on EnglishRussia a week ago: https://twitter.com/EnglishRussia1/status/697017291494596608
It may have existed before this...