Rockfel began her career at the lowest level, being beaten in a selling race, but improved to become recognised as one of the best British racemares of the 20th century.

[2] Rockfel was sent into training with the Australian Oswald Marmaduke Dalby "Ossie" Bell at his Delamere House stable in Lambourn Berkshire.

[3] According to the Bloodstock Breeders' Review, Rockfel was an unusually intelligent and independent horse, leading to her being nicknamed "the old lady", by Bell's stable staff.

[5] In the spring of 1938 Rockfel showed improved form to finish third in the Free Handicap over seven furlongs and then recorded her most important success up to that time when winning the Princess Elizabeth Stakes at Epsom.

[8] Rockfel was brought back in distance for the one mile Coronation Stakes at Royal Ascot in which she failed when attempting to concede fourteen pounds to the winner Solar Flower.

She led from the start and accelerated away from her rivals in the closing stages, winning by three lengths from the Jockey Club Cup winner Foxglove and the St Leger runner-up Challenge.

[10] She began the season by easily winning the March Stakes at Newmarket in spring but then developed training problems and was retired to stud without racing again.

[2] At the end of 1938, Rockfel was rated equal with the Derby winner Bois Roussel, when both were assigned a weight of 133 pounds in the three-year-old version of the Free Handicap.