 In 1969 he appeared as a guest player for Auckland in a match against the New Zealand national rugby league team to mark the New Zealand Rugby League’s diamond jubilee.He made national representative appearances for the Kangaroos in Tests against South Africa in 1963, on the 1963–64 Kangaroo tour and in three matches of the 1968 World Cup.His international rugby league debut in the First Test against South Africa in Brisbane on 20 July 1963 saw Thornett become Australia's 28th dual code rugby international, following Michael Cleary and preceding Jim Lisle.