Decades ago, when the legal media first started reporting law firm results tables, an uncomfortably large proportion of the numbers were estimates. Gradually law firms started to offer some transparency about their financials and once the vast majority became U.K. limited liability partnerships, there was no point in them withholding the information anymore as it would be made public each year.

Except, that is, for Slaughter and May. The famously conservative British stalwart opted not to become an LLP and, as a general partnership, remains the only large U.K. law firm to resolutely refuse to give any financial information. And it has to be said such a tactic has served it well. The firm has retained an air of mystery and its reputation of being extremely profitable has only added to its renown among graduates and clients.