Eastlake played for
Ellerslie in the
Auckland Rugby League competition and also represented
Auckland. Eastlake was a member of the
New Zealand national rugby league team, "the Kiwis", from 1951. He represented New Zealand in 79 games, including 28 tests. In 1954 he was the captain of the New Zealand team at the first
Rugby League World Cup competition in France. During that World Cup competition, Eastlake's qualities were described in the opening game of the tournament, against France (captained by the legendary
Puig Aubert). "The New Zealand captain, C. A. Eastlake, was an inspiration at centre, both in attack and defence. Time and again he halted dangerous back movements by holding
Antoine Jiminez. It was no mean performance to reduce Jiminez, a highly ranked centre last year, practically to impotence. In addition, Eastlake initiated attacks with dash and resource. He showed speed to score New Zealand's second try, while he was also responsible for
R J McKay scoring." Although the game was won by France by 22 points to 13, Eastlake remained optimistic saying, "We will do better now we have some match play. We can still win the cup. We were all a little stiff and the team took a long time to settle down. However, it was a good fast game, and I enjoyed it." Eastlake's optimism was not borne out. He retired following the
1960 World Cup. In the Australian 1963 Rugby League season Eastlake was a
player-coach for a New South Wales country team.{{Cite news ==Honours==