My contender is Lord Peter Taylor (1992 – 96) for his reforms to the legal profession. Here are some important ones:
i) He opened the windows to bring fresh air into the judiciary: unprecedentedly he held a Press Conference following his appointment; he appeared on TVs Question Time; he was a castaway on Desert Island Discs; and he gave the annual Richard Dimbleby lecture on The Judiciary in the 90s.
ii) He supported the removal of wigs for the judiciary. However this did not succeed.
Who would your contender be?