Having competed in the Steeplechase at Glasgow 2014, Eilish switched from the barriers to the flat following a serious foot injury. She was a finalist in both 1,500m and 5,000m in Gold Coast, finishing 6th th in both events.
In the summer of 2018, Eilish followed up her Gold Coast Games by taking silver over 5,000m at the European Championships in Berlin, adding to her European Indoor bronze from the previous year. She was in brilliant form in 2021, erasing Paula Radcliffe's long-standing British 5,000m record at the Oslo Diamond League.
She competed at her third Olympic Games in Tokyo following a debut in the 3,000m steeplechase at London 2012 and qualifying as a finalist in the 5,000m at Rio 2016. She finished ninth in the 10,000m in the Japanese capital 30 years on from her mother Liz McColgan's Tokyo World Championship win.
Eilish won a silver medal in Women's 10,000m at 2022 Commonwealth Games in Birmingham.