Over the next three seasons, Johnston's personal output was an impressive 65 goals from 137 appearances (as well as four caps for Scotland), but this yielded only one minor Glasgow Cup win during the period; arch-rivals Celtic had begun a period of dominance at that time, and overwhelmed Rangers 4–0 in the 1969 Scottish Cup Final less than a month after Johnston had scored a hat-trick against them in a cup tie at Celtic Park. There was further disappointment as the club was twice eliminated from the latter stages of the Inter-Cities Fairs Cup by English opponents, both of whom went on to win the trophy (Leeds United in 1968, Newcastle United in 1969). Johnston missed the home leg against Newcastle through suspension after he was sent off in the previous round against Athletic Bilbao.