The men are thought to be Russian and Georgian, most likely ex-KGB. But according to Dmitry Fonarev - himself a former KGB agent who now works with the National Bodyguard Association of Russia, and has guarded Bill Gates and Henry Kissinger - British ex-SAS servicemen are the usual choice for visiting billionaires.
"Trustworthiness is a very serious question. British guys are just working for money and they don't care about politics, they get good money to keep their mouths shut,"he says.
Their wages are about £120,000 a year, according to Mr Fonarev, typically on a six-month contract. They are well looked-after too. The Independent observed Mr Berezovsky's heavies retiring to a conference room for a lunch break this week, shortly followed by a huge consignment of high-end sandwiches.
It is well earned; looking after these people is a deadly serious business. Berezovsky has suffered many assassination attempts, including a car bomb in 1994 that decapitated his driver and seriously injured one his bodyguards.
However, while the common image of this profession is servants loyally taking bullets, Mr Fonarev said this is a Hollywood fallacy.
"We take some risks... but we sell our skills and not our lives," he said.
"If you stay in front of your VIP in the line of fire, the first shot will be yours and second will be his, so there is no reason to do that - we are not shields," he added.
Brawn is not the only requirement. "You can have a big guy with a big gun, but he has no brain and so he can't understand what he has to do," said Mr Fonarev. "It makes no sense to train him to be a bodyguard, he can be a nightclub bouncer."
In the meantime, the body guards are a strange - and sometimes an unnerving - presence in the courtroom, as The Independent found out this week when one bodyguard made a sudden appearance in the press gallery and this reporter needed to squeeze past him: "Er, excuse me."