He won five caps for Wales and was selected for the British Lions 1910 tour of South Africa, though he did not play in any of the test games.

He captained Newport during the 1920/21 season and was part of the team that faced three touring sides; the 1906 and 1912 South Africans and the 1910 Australians.

Plummer was first capped for Wales on 3 February 1912 when he played against Scotland at St Helens under the captaincy of Dicky Owen.

It was an excellent game from a Welsh viewpoint as the team beat Scotland 21-6, and Plummer himself scored a try.

Plummer was later selected against the touring South African team, as he done so for Newport two months earlier.