While still studying at Cambridge, Warr was selected for the 1950–51 tour of Australia. He played in two of the five Test matches, with the worst debut bowling performance in Test cricket, taking no wickets but conceding 142 runs, a record which stood until 2009 when Australian Bryce McGain went wicketless while conceding 149 runs against South Africa. He went on to take just one wicket, that of Australia's number seven, Ian Johnson, caught behind. In those two matches, he conceded 281 runs, the worst bowling figures of any Test cricketer in history until the record was surpassed in 1985 by Sri Lanka's Roger Wijesuriya. his bowling average remains the worst of any retired England Test player; only Ravi Bopara has a worse average. According to the 1952 "Wisden Cricketers' Almanack" Warr "tried hard and cheerfully, but he could not be regarded as Test class."