Isobel Giles was born on 28 August 1908. She trained as a teacher and gained the Board of Education Elementary Teachers' certificate at Avery Hill College, London. She was an active Methodist Church member in Brunswick, Leeds, whilst teaching in a 'slum school' there. She was accepted as a missionary candidate for the Women's section of the Methodist Missionary Society in the autumn of 1933 and began her training at Kingsmead College, Birmingham, shortly afterwards. She arrived in India in 1935 and began her career at Karur within the MMS Trichinopoly District. Her work was predominately educational but she was involved in some evangelical work. In 1937 she relocated to Dharapuram working in the industrial school for girls where she taught 'homecraft' and for most of her tenure was also the principal of the school.
In 1940 she arrived in England on furlough. She should have returned to India at the end of 1941 but a combination of restrictions (sometimes prohibitions) on women gaining passage on ships to India and her parents’ poor health meant she remained in England. In the autumn of 1942 she took up a temporary teaching post in Derby but still with the intention of continuing her missionary career when possible. In January 1944 she declined an opportunity to return to India and in August she formally left the MMS. She died on 2 January 2009.