Docker was born in Cardiff but lived in London[2] and was a member of the Middlesex Ladies Athletic Club.[3] and by 1958 was a 11-times Welsh champion over 100, 220 and 440 yard and the long jump.[4] Docker married Edward Whitehead in London during 1957 and competed under her married name thereafter.
In June 1958 Whitehead represented South Wales against North Wales in a warm up event before the Empire Games, winning the 220 yards event and finishing runner-up behind Bronwen Jones in the 100 yards event.[5] She also won the double at the 1958 AAA Welsh championships, winning both the 100 yards and 220 yards events (her 12th and 13th titles).[6]
She represented the 1958 Welsh team[7] at the 1958 British Empire and Commonwealth Games in Cardiff, Wales,[8] where she participated in three events;[9] the 100 yards, the 220 yards[10] and the 4 × 110 yards relay, with Bonny Jones, Ellen Grainger and Gwyneth Lewis. In the relay the Welsh team were denied a place in the final after being disqualified following an illegal baton change.[11]