William Thomas Mainwaring (born Gwilym Thomas Mainwaring; 24 January 1941 – 1 April 2019)[1] was a Welsh international[2] second row rugby union player who played for Aberavon RFC.
In the following season, he was one of four Aberavon RFC players who played against the touring All Blacks (the others being fellow second row Max Wiltshire, centre Ian Hall and debutant full-back Paul Wheeler).
During his career he formed a formidable club second row partnership firstly with Max Wiltshire and later with Allan Martin, both fellow internationals.
His mother, Evelyn Mainwaring, who died in 2004, was a vociferous supporter of Aberavon; her "often deafening" words of advice and humour delivered from the stand made her popular throughout the rugby fraternity in Wales.
On one occasion, when her son got into a fracas with Gareth Edwards, she shouted: "Put him down, Billy, he's playing for Wales on Saturday!