Gilligan played for Sussex throughout the 1921 season and according to "Wisden" "made a distinct advance". His batting record was similar to the previous season, although he increased his number of wickets in the season to 90 at an average of 30.64. "Wisden" notes that his bowling was not statistically good, but that his biggest impact came in fielding, which was "brilliant in the extreme. He was described on all hands as the best mid-off in England." In 1922, Gilligan assumed the Sussex captaincy from Herbert Wilson. The team's results were not impressive, but "Wisden" said that the team were attractive to watch and excelled in fielding, in which Gilligan led by example. Gilligan later recalled that he received great support from George Cox, the senior professional in the team. Personally, Gilligan had his best season to date with bat and ball; he scored 916 runs and took 135 wickets at an average of 18.75. Based on his good form, he was selected in the prestigious Gentlemen v Players match at Lord's. Appearing for the Gentlemen, a team of amateurs, his fielding in particular impressed commentators. He was selected in a further representative match, when he played for the "Rest of England" against Yorkshire, the County Champions. In the latter game, he took eight wickets in total. At the end of the season, Gilligan was included in the MCC team to tour South Africa and play a Test series.