Lord Ardlaun’s estate was inherited by his nephew, Bishop Plunkett who subsequently sold a large portion to Dublin Corporation in 1939. The northern portion was developed for housing, the Corporation retained the southern portion and the main residence which was burnt down in 1943. This southern portion of the site was developed as St. Anne’s Park by the Corporation. The north western portion of the overall site was retained by Bishop Plunkett, it contained Sybil Hill House. It was developed as a secondary school for boys opening in 1950 with Sybil Hill House at its core and surrounded by playing fields. The school expanded in the following years to include multiple facilities.