The FTSE 100 has been the bellwether of the nation's fortunes throughout a decade characterised by dynamism, as well as uncertainty. And whether prospering or confronting hard times, the U.K.'s public companies have turned to law firms whose own reputations have long been tied to the country's key share indices.

Using data provided by information company Adviser Rankings, Law.com's Legal Week compares figures from the first quarter of 2010 to the last quarter of 2019 to establish who among the country's top corporate advisers have managed to retain, or indeed gain, the most listed companies on their books over the course of the decade.

The 10-year period has seen some law firms demonstrate unrivaled consistency. Slaughter and May continues to dominate the tables, comfortably topping the FTSE 100 and 250 adviser rankings in the latest quarter. Having added a net of two listed clients in 10 years, the Magic Circle firm now counts a third of the top index's companies as its clients (33), and has added another eight clients to its FTSE 250 roster for a total of 46.