I doubt that a bit. The site appears to merely rank chambers according to the number of recommendations by the book's authors, rather than banding individuals.
First thing I thought of was how barristers are ranked for prosecuting. The more able and experienced they are, the more serious the cases they are allowed to prosecute. So the most junior are allowed petty thefts and taking and driving away cars, and the more senior are allowed to prosecute rapes and the most senior are allowed serious fraud and murders.
Most solicitors who defend will ask for a ten year man/ woman or whatever experience they think the case demands. In a lot of chambers, there's an informal way of ranking seniority; the letter box ! When a barrister joins, their name is painted on the outer door, below everyone else's. As the oldest retire their names are removed and everyone moves up. The letter box is just above half way up, so when their name gets above the letter box, they have some seniority ; they are above the letter box!