In 1929–30, ill-health restricted Jackson to just five first-class matches and five innings for Balmain. Despite his health, Jackson had a successful season, and scored 168 not out against Arthur Gilligan's English team, which toured Australia briefly "en route" to New Zealand. He was seen as an automatic selection for the 1930 Ashes tour of England. He confirmed his selection with 182 in a Test trial, an innings regarded by many as the best he had ever played. Another scare with illness saw him hospitalised in Adelaide after the Christmas match against South Australia, missing the next two state matches. His health problems continued after an operation to remove his tonsils; a procedure that was arranged by the Australian Board of Control despite Jackson never having previously suffered any problems with his tonsils. Bill Ponsford had suffered from tonsillitis during the previous tour and the Board were anxious to avoid similar occurrences. Complications resulting from the operation saw Jackson lose a stone (6.4 kilograms) in weight.