Sir Samuel Romilly, after whom the Association was first named, was for a short time solicitor general and a well-known 19th century law reformer. 

Admitted to the bar in 1783, he soon developed an extensive practice in the court of chancery. Philosophically he was in sympathy with the views of Jean-Jacques Rousseau and he knew several figures of the Enlightenment, including Diderot and Jean d'Alembert. Romilly's enthusiasm for the French Revolution inspired his Letters Containing an Account of the Late Revolution in France (1792). 

His Thoughts on Executive Justice (1786), which developed the views of Beccaria, signalled the start of his efforts to reform the law. In 1806 as solicitor general in the cabinet of Lord Grenville, he initiated improvements in bankruptcy practice, and later was instrumental in reducing the penalty for many comparatively trivial offences (e.g., pickpocketing) that at that time were subject to capital punishment. The immediate results of his efforts at reform appeared small, but during Victoria's reign many of his proposals were adopted.

Further reading:
Memoirs of the life of Sir Samuel Romilly, written by himself; with a selection from his correspondence; edited by his sons. (1840) 
P. Medd, Romilly (1968) 
R. D. Henson, Landmarks of Law (1960).