He also represented his state in Australian rules football and rugby union.
He represented the Australian military in rugby union.
At an early age he excelled at most sports, and represented his country in rugby union and hockey at schoolboy level.
As a youth, he represented West Midlands county in rugby union.
Whilst at Guy's Hospital Tweed represented the medical school in rugby union.
John was an all-round sportsman and represented Scotland at international level in rugby union.
His brother Darby Loudon also represented for Australia in rugby union and captained the national side.
He represented his country in both rugby league and rugby union.
He was the first New Zealander to represent his country in rugby league then in rugby union.
Prior to switching to rugby league he represented for his state in rugby union.