Troubles in the local coal industry and the Great Depression meant that many parents could not afford to pay the bare minimum school fees while wealthier Catholics chose to send their children to public schools.

Originally located in Splott, it moved out of its cramped school grounds to a new campus overlooking the Bristol Channel in the 1960s.

It was called St Joseph's Grammar School at that time and located at David Street, Cardiff.

[3] In 1987 St Illtyd's and Heathfield House merged to form the present coeducational school.

[4] Caer Castell Camp is a motte and ditch scheduled monument and dates back to between 1066 and 1540 AD.