Philpot was born in Clapham, London, but the family moved to Herne in Kent shortly afterwards. He was a practising Christian who converted to Roman Catholicism.
Philpot studied at the Lambeth School of Art in 1900 where he was taught by Philip Connard, and at the Academie Julian in Paris.
One of the leading portraitists of his day, Philpot became an establishment artist, made wealthy through lucrative commissions. He was elected to the Royal Academy of Arts in 1923.
However things were to change. In 1933 the Academy rejected his paintings The Great God Pan and Guardian of the Flame because of their explicit sexual content which led to a dramatic downturn in his popularity.
Philpot’s artistic character also changed. Tensions between his public life of strict Christian observance and academic painting, and his private homosexuality, and desire for artistic experiment, precipitated a crisis in his career. He was, primarily, an observer of the human form, and risked public censure by depicting sexuality.
His loss of commissions led to financial hardship for the rest of his life. He died of a stroke in 1937, and his lover, Vivian Forbes, committed suicide the day after his funeral. Philpot is buried in St Peter’s churchyard, Petersham.