 In 1977, Lannaman was ranked second only to world record holder Marlies Göhr in the 100 m. In the European Cup of that year she was second in both the 100 and 200 m and in the inaugural World Cup, second again in the 100 m and first in the 4 × 100 m representing Europe.She also ran the fastest ever electronically timed 100 m by a British woman with 10.93 sec in Dublin, which was wind assisted (+3.8), so did not stand for record purposes.In 1978, Lannaman won the 100 m gold medal and 200 m silver medal in the 1978 Commonwealth Games for England and for Great Britain in the 1978 European Championships won a silver in the 4 × 100 m relay with teammates Kathy Smallwood-Cook, Beverley Goddard and Sharon Colyear.