The Sisters of Mercy in Brentwood bought a holiday home in Frinton-on-Sea in 1924, and then in September 1926 they established St. Philomena's School in a bungalow in Pole Barn Lane, under Sr M Gabriel Roche. At the start the school was very small, with no more than 20 pupils, of whom only a few were Catholic. However as the convent became more popular as a holiday home, and as more provision was needed at the Convent an extension was blessed and opened by Bishop Doubleday. Sr M de Pazzi Slattery took charge of the school in 1928, Sr M Anthony Shepherd took charge of the junior pupils and Sr M Bernard Lauterbach took charge of the seniors.

It became obvious over the years that St. Philomena's School required a more permanent setting and that its future would be more secure if it restricted its roll to day pupils. Consequently, 53 Hadleigh Rd was leased for this purpose and on 8 Feb 1936 the school transferred to this new site, re-opening as St. Philomena's Convent Day School. The building itself was purchased on 9 March 1938, by which date there were 19 children at the school (9 Catholics). It was extended the following year, with the addition of a hall and classroom for the sum of £250.

During the war years the convent and school were closed. The school buildings were used by the army. In June 1940 bomb damage was sustained by both the convent and chapel. In May 1946 the convent, guesthouse and school were re-opened. Sr M Cecilia Brennan resumed her office as Superior and Sr M Benedict Lynch took charge of St. Philomena's. Much work was required to return the convent and school buildings to a fit state for their proper use but such progress was made that by 1951 there were 54 children on roll, 26 of whom were boys.

By 1957 Sr Cecilia Brennan was still Superior and Sr M Brigid Barry who had earlier taught at St Edward's School in Romford was Headteacher, assisted by Sr M. Juliana Cassidy.

The life and work of St Joseph's Convent and St. Philomena's School continued to prosper throughout the 1960s. By 1973 there were three sisters in St Philomena's - Sr M Brigid - Headteacher, Sr M Juliana Cassidy - Teacher and Sr M Goretti Glynn - Teacher. By 1975 Sr M Angela Holton was appointed Headteacher with Sr Vianney Carroll as her Assistant. She was succeeded by Sister Marie Raymond in 1982.

Early in 1987 St Philomena's Educational Trust was formed to maintain the smooth running of the School and to continue the high ideals set by the Sisters. The first lay Headteacher, Mrs Josephine Geldard, was appointed to St. Philomena's School. Mrs Bernadette Buck succeeded her in 1992. In 1996 the School established Clover House in a neighbouring property. This was named after Father Donald Clover who was Parish priest for 43 years until 1995 and was a great supporter of the School. This was followed in 2002 by the addition of Jubilee House which now houses the School's Resource Centre for Art, Music and Science.