As a child, her parents were caretaker and head cook at
St Thomas More School in nearby
Grenoside. Sherwood attended Yew Lane Secondary Modern, where at the age of fifteen she was appointed as Head-Girl. After a successful set of O-Level results, she transferred to nearby
Ecclesfield Grammar School to study for her A-Levels. Parkin first came to prominence as an athlete as a 16-year-old as a member of the Sheffield-based
Sheffield United Harriers athletic club. She created an English Schools long jump record in the summer of 1962. On the strength of this she was selected to represent Great Britain against Poland in August 1962 where she finished second behind former world record holder Elzbieta Krzensinska by just 2 cm. This performance started her long and distinguished career as an international long jumper, as it resulted in selection for the 1962
European championships in Belgrade, where she finished 12th, and then representing
England in the long jump at the
1962 Commonwealth Games in
Perth, Western Australia, where she achieved 5th position. Sherwood's early career saw only a slight improvement in her jumping, and she was eclipsed by fellow British jumper
Mary Rand on many occasions, such as finishing second behind her at the
1963 WAAA Championships and
1964 WAAA Championships. At the 1964 Olympic Games in Tokyo, she represented
Great Britain, finishing 13th behind gold medal winner Mary Rand. However, it was in Tokyo that Sheila met British hurdler
John Sherwood and a romance began. Parkin's relationship with Sherwood coincided with improvement in her jumping performances. She took the silver medal at the
1966 Commonwealth Games in
Kingston, Jamaica, behind Rand. Parkin married John Sherwood in 1968 and competed under her married name thereafter. Shortly after her marriage Sherwood became the
national long jump champion after winning the British
WAAA Championships at the
1968 WAAA Championships and later in October at the 1968 Olympic Games in Mexico City, she represented
Great Britain, where she took the silver medal behind the Romanian
Viorica Viscopoleanu with a personal best leap of 6.68 metres. Sherwood took the gold medal at the 1970 Commonwealth Games in
Edinburgh with a career best jump of 6.73 metres and finished fourth at the
1971 European Championships in Helsinki. She regained her WAAA title in 1971 but in her latter years in the sport she was hindered by back problems. Despite this she was selected for the
1972 Olympic Games in Munich where she finished a commendable ninth. Her career as an international long jumper came to a conclusion at the
1974 Commonwealth Games in
Auckland where she took seventh place. == Retirement and personal life ==