Mr Justice William Charles has been given the unenviable task of deciding whether the flotation of Rosneft, the Russian oil giant, is legal. In response to a challenge from Yukos, the rival oil company, he is examining whether the Financial Services Authority and the London Stock Exchange have acted lawfully in allowing Russia’s biggest initial public offering to go ahead.

A lawyer for Yukos yesterday argued that the listing would amount to money-laundering, as 70 per cent of Rosneft’s value comes from the unlawful seizure and sale of Yukos.

Mr Justice Charles has set aside a day-and-a-half to investigate complex legal issues over whether the FSA and LSE decisions are open to legal challenge and has said that a decision is unlikely to come before tomorrow’s deadline.

Rosneft, which has already begun trading on the Moscow market, is due to list on the LSE tomorrow. It is expected to raise $10.4 billion through the flotation, making it the fifth-biggest IPO in the world.

Educated at Malvern College and then Christ’s College, Cambridge, Mr Justice Charles was called to the Bar at Lincoln’s Inn in 1971.

He was junior counsel to the Crown Chancery between 1986 and 1989 and, after that, served as first junior counsel to the Treasury in Chancery matters until 1998. Now 58, he was made a Judge of the High Court in 1998, with a focus on the family division.

Married to Lydia, he has a son, Simon, and a daughter, Florence. He relaxes by playing sport, especially golf and tennis.