She lived in Ghana and later in Greece where as a teenager she competed internationally in the pentathlon and her running ability was encouraged and developed.
In 1987 Diamantides completed her first Bob Graham Round (BG): to run 66 miles (106 km) over 42 Lake District peaks within 24 hours.
[2] Later that year she and fellow fell-runner Alison Wright went to Nepal to attempt to break the record for running from Everest Base Camp to Kathmandu.
The first was the Paddy Buckley which was completed in 20 h 8 min; beating the men's record (held by Adrian Belton) by two hours.
In 1990, Diamantides set a course record in the Wasdale Fell Race, which stood until 1997 when it was beaten by Mari Todd.