In 1885, the Wellington Sisters of Mercy were asked to set up a new convent in Blenheim. The Parish wanted the Sisters to take charge of St Joseph’s Girls School, which has been opened in 1872.

Then in 1896 the Sisters were asked to take over the running of St Mary’s Boys School, which had also been open since 1872.

In 1973 the two schools were merged and became St Mary’s School.