In 1897, Saint Felix School was founded by Margaret Isabella Gardiner with the support of suffragist Millicent Fawcett. The school was based at a house called ‘Westhill’ in Aldeburgh and had just four students. The house was owned by Dr Elizabeth Garrett-Anderson who was the sister of Millicent Fawcett, the first female British physician and surgeon and the Mayor of Aldeburgh, to name just a few achievements.

In 1898 the school relocated to Southwold. The first buildings used were: The Elms (now May Place), Gorse View (St Barnabas) and Golf Links House (previously the Golf Links Hotel, now Regency House). These were quickly followed by Uplands (Dunburgh House), Blyth House and Southwold House (The Lodge). Saint Felix was beginning to settle in to its new town with Miss Gardiner as Headmistress.

1902 saw the initial construction of the current school buildings which was the first purpose-built premises for the School. Since then the school has developed, adapted and expanded to suit the needs of the School.

Following a prolonged period of ill-health, Miss Gardiner resigned and was succeeded by Lucy Silcox who enjoyed a colourful cultural and social life on the fringes of the Bloomsbury set. Her friends included Lady Ottoline Morrell, Augustus John, Walter Sickert and John Masefield who wrote the words of the School song for her. The music was composed in 1924 by Etta Addis, an Old Felician.

Miss Silcox’s term as Headmistress saw the construction of the Library and Gardiner Hall, the evacuation of girls during the war and the purchase of modernist paintings and sculpture. Notable works of art included a sculpture by Mestrovic and work by Christopher Wood which inspired students.

Miss Silcox demanded change and was a role model as President of the local National Union of Women's Suffrage Societies, supporting women gaining the vote.

Following the outbreak of war, the school was evacuated firstly to the Moffat Hydro Hotel in Scotland and then moved to The Hayes at Swanwick in Derbyshire.
After the war when the school had returned to Southwold, a small branch of the school was established at Penmaenmawr in North Wales; some parents were still worried about zeppelin raids along the east coast and thought their daughters would be safer in North Wales.

Centre Cliff House, formerly a hotel, was acquired in 1919 for use as the Junior School. The House is located on the seafront in Southwold.

In 1920 the ‘Sunk Garden’ was created as a memorial to five Old Felicians who lost their lives in the First World War. The work was carried out by Bertha Steadman, then in charge of grounds, and her team of groundsmen. Miss Maia Bond, an Old Girl on the staff, helped Miss Silcox take measurements and Mademoiselle Buquet supplied the French words for the sundial.

During the time of Miss Edghill as headmistress, the School was attended by Betty Cowell who went on to become the first female television announcer. The Hon. Alexander Shaw (later 2nd Lord Craigmyle) was the Chairman of the School Council from 1931- 34 and the donor of the Chapel and Cloisters.

In 1935, Speech Day was attended by the Chairman of the School Sir Ernest Gowers, Lady Shiffner and Lloyd George. Sir Ernest Gowers GCB, GBE, KCB, KB was the third Chairman of the School and was married to Constance Greer, one of the first four boarders to attend the school.

The school was requisitioned by the military during the Second World War at which time it served as a rehabilitation centre and also as a co-ordination base for Force L in preparation for the D-Day landings.

The school was prepared for War with bomb shelters. The shelters were prepared with hammocks, provisions and recreational material such as books and puzzles.

In 1940 there was an evacuation of students to Tintagel, Cornwall and Hinton House in Hinton St George, Somerset.