Colwell's mother was Roman Catholic from Northern Ireland, and her father was an Anglican from Stoke-on-Trent.
In 2016, Colwell undertook a 500 miles (800 km) walk from Lough Erne, near Enniskillen to Boston, Lincolnshire, to find out why the Eurasian Curlew (Numenius arquata) is declining so rapidly across Britain and Ireland.
[23] In March 2021 she was appointed chair of the Department for Environment, Food and Rural Affairs initiated Curlew Recovery Partnership England,[2] a roundtable of organisations charged with restoring Curlews, their habitats and associated wildlife across England.
[24] She led the successful campaign to establish a GCSE in Natural History,[25] announced by the government in April 2022.
[26] Colwell is a spokesperson for environmentalism in the United Kingdom and writes articles on the subject in journals, magazines and newspapers.
[30] Colwell has campaigned with politician Caroline Lucas and educationist Tim Oates [31] to establish a GCSE in Natural History.