When she reappeared a few days later in the Princess Elizabeth Stakes at Epsom Downs Racecourse she was equipped with a hood and finished fourth behind the subsequently disqualified Be Sweet.
Moved up in distance for the Group Three Musidora Stakes at York Racecourse in May the filly finished fourth behind the Barry Hills-trained Princess of Man.
[7] In June, Swiss Maid (now racing without a hood) was dropped in class and recorded her first victory, winning the Twyford Stakes over ten furlong at Newbury Racecourse.
[7] Swiss Maid then appeared at Newmarket in early October when she ran in the ten furlong Sun Chariot Stakes, which was then a Group Two race.
After a respectable performance in the Benson and Hedges Gold Cup at York in August, when she finished fourth behind Troy, she was unplaced in her last three races.
[11] In 1978, the independent Timeform organisation gave Swiss Maid a rating of 129, making her their top-rated three-year-old filly of the season.
In the inaugural International Classification, a collaboration between the official handicappers of France, Ireland and the United Kingdom, Swiss Maid was rated the best three-year-old filly in Europe ahead of Reine de Saba and Dancing Maid and the join-fifth best racehorse of any age behind Alleged, Ile de Bourbon, Acamas and Shirley Heights.