Philpot was born in ClaphamLondon, but the family moved to Herne in Kent shortly afterwards. Although homosexual, Philpot was a practising Christian who converted to Roman Catholicism.
Philpot studied at the Lambeth School of Art (now known as City and Guilds of London Art School) in 1900, and at the Academie Julian in Paris. He first exhibited at the Royal Academy in 1904 and was elected to that establishment in 1923. He was a member of the International Society from 1913 and in that year he was awarded the gold medal at the Carnegie Institute, Pittsburgh. Some of his later work was considered controversial in its time because of the explicit sexual imagery, and this led to a loss of popularity which caused him financial hardship.