After the First World War expansion of the fledgling parish took place in the form of a lease on a tin building at the bottom of Nevill Road, formerly the 'Rottingdean Sanitary Laundry', which was converted to a chapel. In 1925, the Sisters opened the substantial Convent of St Martha much further up the High Street, facing The Green. These are the premises we are familiar with today.
The school they opened served the needs of many local children, a significant proportion of them non-Catholic, for the next 40 years. Then, however, changing educational requirements and rising fees for lay teachers meant the nuns could no longer continue. Yet their tradition was maintained when in 1969 the present, highly successful, Aided RC Primary School of Our Lady of Lourdes arose on part of their land. Some of their buildings were even taken over.