Davies first played rugby for Wales Secondary Schools, alongside his cousin and future Welsh captain, Haydn Tanner.
When Wales won, thanks to a Vivian Jenkins penalty goal, he found himself as part of that year's winning Home Nations Championship team.
Frank Whitcombe, Willie's Welsh teammate and fellow Lance Todd Trophy winner took on the role of 'minder' for Northern's slightly-built, mercurial stand-off when he was targeted by opposing teams.
[6] Wales - rugby union[7] Willie Davies played, and was man of the match winning the Lance Todd Trophy in Bradford Northern's 8–4 victory over Leeds in the 1946–47 Challenge Cup Final during the 1946-47 season at Wembley Stadium, London on Saturday 3 May 1947, played stand-off in the 3–8 defeat by Wigan in the 1947–48 Challenge Cup Final during the 1947–48 season at Wembley Stadium, London on Saturday 1 May 1948,[8] and played in the 12–0 victory over Halifax in the 1948–49 Challenge Cup Final during the 1948-49 season at Wembley Stadium, London on Saturday 7 May 1949.
He qualified as a games and geography teacher at Carnegie College of Physical Education, Leeds and then taught at Bingley Grammar School.