Mantle played in the early games of the tour, including wins over East Africa in Nairobi, and Boland at Wellington.
John Mantle played at prop in St. Helens' 2–25 defeat by the 1975 NSWRFL season premiers, Eastern Suburbs Roosters in the unofficial 1976 World Club Challenge at Sydney Cricket Ground on Tuesday 29 June 1976.
John Mantle played loose forward in St. Helens' 35–12 victory over Halifax in the Championship Final during the 1965–66 season at Station Road, Swinton on Saturday 28 May 1966, in front of a crowd of 30,165.
John Mantle played loose forward and scored a try in St. Helens' 21–2 victory over Wigan in the 1966 Challenge Cup Final during the 1965–66 season at Wembley Stadium, London on Saturday 21 May 1966, in front of a crowd of 98,536, and played at second-row in the 16–13 victory over Leeds in the 1972 Challenge Cup Final during the 1971–72 season at Wembley Stadium, London on Saturday 13 May 1972, in front of a crowd of 89,495.
John Mantle played at second-row in St. Helens' 2–2 draw with Warrington in the 1967 Lancashire Cup Final during the 1967–68 season at Station Road, Swinton on Saturday 7 October 1967 (replaced by Kel Coslett in the replay), and played at second-row in the 4–7 defeat by Leigh in the 1970 Lancashire Cup Final during the 1970–71 season at Station Road, Swinton on Saturday 28 November 1970.