[4] An orthopaedic surgeon by profession, Williams continued to be involved in rugby following his retirement, serving as president of the Bridgend Ravens.

[5][8] As an adult amateur, Williams participated in the first event of the tennis Open Era, the 1968 British Hard Court Championships in Bournemouth, but lost to Bob Howe in the first round.

In an interview years later, Williams stated that "If I had to make the decision now, I might have opted for tennis," but admitted that his lack of a big serve would have hindered any chances of success.

[9] Williams' focus moved from tennis to rugby union, which was an amateur sport, in order to pursue a career in medicine.

[12] Williams had many high points in his career, being a key player in a Welsh side that won Grand Slams in 1971, 1976 and 1978, and is particularly remembered for his record against England.

[13] He was also outstanding for the Lions, scoring an important long-range drop goal in the fourth test of the 1971 series against New Zealand.

[15] Williams chose not to go on the 1977 British Lions tour to New Zealand, after being advised by his consultant to focus on his medical career.

[23] In January 2006, in a party of 16 Welsh men and women, he climbed Mount Kilimanjaro in Tanzania for charity, helping to raise more than £200,000 for the NSPCC's 'Full Stop' Campaign.

[24] Williams died from bacterial meningitis, after a short illness, on 8 January 2024, at the age of 74 at the University Hospital of Wales in Cardiff.