LONDON—When Roman Abramovich landed in London in 2003 with the intention to buy one of the city’s soccer clubs, all the sellers knew about him was what they found in a cursory Google search. He was Russian. He had made a fortune running the Sibneft energy company. And he had ties to Russian President Vladimir Putin.
Beyond that, Mr. Abramovich was a mystery wearing a scruffy beard and jeans, according to people who were present.
