He was the eldest son of Thomas Richards and his wife, Catherine, whose brother (William Parry) was warden of Ruthin, Denbighshire.
His grandfather, also called William Parry, was headmaster of Ruthin School and Richards was educated there.
During his parliamentary career, he supported the ministry of William Pitt the Younger but made only one reported speech, opposing the Quakers' Relief Bill on 24 February 1797 as unnecessary and inconvenient.
He was one of the three registrars to the Prerogative Court of the Province of Canterbury from 1788 to 1800, and was appointed counsel to Queen Anne's Bounty in 1789.
However, Eldon instead bowed to party-political pressure and appointed the Attorney General, Thomas Plumer, to the new post.
The offer was apparently made when Lord Eldon tossed a note into court addressed to "Taffy".
On the death of Sir Alexander Thomson, Richards became Chief Baron on 21 April 1817 and became a Privy Counsellor five days later.