Gillespie occasionally proved his worth with the bat, with a highest Test score of 201 not out and an average of 18.73. He is the only player in Test cricket with a career batting average of less than 20 to score 200 runs in an innings. He demonstrated a solid defensive game, known by teammates as 'The Walking Forward Defence', and despite not regularly making big scores, he was a difficult batsman to dismiss and occupied the crease for substantial periods of time, allowing his batting partners time to get bigger scores. His low back lift helped him to defend or deflect shots from spin bowlers more readily.