Her senior breakthrough came in 1990 when she finished second at the AAAs National Championships in 57.43, behind Gowry Retchakan"s 57.14. A month later, she again finished second to Gowry Retchakan at the AAAs Championships, running a lifetime best of 56.15 secs to earn World Championship selection.
She represented Great Britain at the World Championships in 1991 and 1993. This performance earned her selection for the European Championships in Split, where she ran 56.84 in her heat to reach the semi-finals. In her semi-final she ran 57.06, failing to reach the final.
At the 1991 World Championships in Tokyo, she was eliminated in the heats in a disappointing 57.81.
She began the 1992 season by finishing third at the United Kingdom Championships behind Retchakan and Louise Fraser, running 56.99. She then narrowly missed Olympic selection by finishing fourth at the AAAs Championships, which incorporated the Olympic trials.
The final Olympic place went to Louise Fraser, as she edged out Parker 56.30 - 56.35. Parker was named as an Olympic reserve.
Parker finished second at the 1993 United Kingdom Championships in 57.14, behind Gowry Retchakan.
At the 1993 World Championships in Stuttgart, she ran 56.93 in her heat to reach the semi-finals, where she was eliminated running 56.68. She then finished second at the 1994 AAAs Championships, once again behind Retchakan, 57.14 - 57.31, to earn selection for the 1994 European Championships in Helsinki. At the Europeans, she was eliminated in the heats with 57.83.
A few weeks later, she reached the final at the in Victoria, finishing sixth in 56.72.
Parker was a member of the Essex Ladies Athletics club (now Woodford Green with Essex Ladies).
