St. Marys School was started at 8 Broad Green (the old Presbytery) in 1851, the first Chatelaine of the school arriving from the Convent of the Faithful Virgin (Virgo Fidelis), Norwood, on a cart drawn by a donkey. In the first week it had eight pupils. Shortly, it moved into an adjoining cottage.
The school was entirely voluntary until 1862, in which year it received State recognition; the following year it also received its first State aid.
On 3 July 1864 the school transferred to its present site and from January 1888 passed into the care of the Sisters of Mercy. From 1904, there was a separate Infants Department, perhaps until 1936. In 1939, the school was evacuated to Latcham, Sussex and then after Dunkirk, to Addlestone, Surrey, and later to Withiel, Cornwall. In 1955 pupils over the age of 11 were transferred to a new and separate Secondary School which became ST MARYS (RC) HIGH SCHOOL).
In 1968, the Primary children moved into a new building, separate Infants and Junior Schools being created at that point.