At the peak of his career, Gilligan was a fast bowler. He bowled with his arm quite low, but was very accurate; his usual strategy was to aim at the stumps or to try to induce the batsmen to edge the ball to be caught in the slips. According to his "Wisden" obituary, he "regarded it as a cardinal sin to bowl short". Following his injury, he could not reach his former speed and was reduced to medium pace. In this style, he continued to have some success at county level. His batting was based mainly around driving the ball. He batted low in the order, and tried to score quickly, particularly against fast bowling. Several of his centuries were scored against the most successful teams, and often in difficult situations. He excelled as a fielder; his "Wisden" obituary stated: "At mid-off he has had few rivals".