Deirdre O'Loan

Sister Cecilia Maria Deirdre O'Loan She studied at the Convent of Mercy in Kanturk. Her father was then advising the Sisters of the Infant Jesus of Drishane Convent on agriculture, and she developed a positive impression of the institute after meeting some of its members. On her father's encouragement, she began attending the boarding and technical school there and developed a greater admiration for the sisters. She began attending the University of London in 1972, graduating the year after with a Postgraduate Diploma in Library and Information Studies. She began teaching the school's A-level classes when they were introduced the year after, and volunteered with the Red Cross during the 13 May incident. With the introduction of Malayisation, she was forced to leave Malaysia in 1972. She was then asked to help set up the Catholic Junior College (CJC) in Singapore. O'Loan briefly taught English, Literature and General Paper at the CHIJ Katong Convent

In December 1987, it was announced that O'Loan would succeed Brother Joseph Kiely, who was to be transferred to St. Joseph's Institution as deputy principal, as principal of CJC on the school's reopening in January. This made her the first Catholic nun in the country to head a junior college. Kiely was supportive of the appointment, opining that O'Loan was "eminently qualified with all the disposition for the job." She felt that the students of CJC were unfairly dismissed as "fun-loving, outgoing and rather frivolous" and "without a sense of responsibility."

O'Loan was conferred the Public Administration Medal (Bronze) at the 1992 National Day Awards. From 1992 to 1994, she chaired the Conference of Junior College Principals. O'Loan stepped down as principal in late 1994 and instead became the supervisor to the 11 CHIJ schools in the country. As supervisor, she advised the principals of CHIJ schools in "[upholding] the mission and motto" of their schools. She was known to regularly attend school events. In 2014, she was conferred the Public Service Star for her contributions to Singaporean education.

Personal life and death O'Loan was affectionately nicknamed "Sister D". She died of pancreatic cancer on 13 August 2016 at the CHIJ Convent on Chestnut Drive. The wake was held there two days after, while the funeral mass was held at the Saint Joseph's Church in Bukit Timah on 17 August.