According to Calderon's record book, The Letter is set in the bedroom of one of Henry VIII's ill-fated wives, Anne Boleyn. The entry reads as follows: "Morning Letters - girl in grey dressing gown seated "Anne Bolyn's (sp) bed" (so called) at Hever Castle (Chas. Dickens Esq.)…painted with varnish and drying oil mixed together in a pot. Cabinet size 34 X 28". 1866 was a very good year in the artist's career and Hever and its surroundings figure in a number of other painting executed during his stay including, Hall at Hever Castle, Dairy at Hever Castle, Long Gallery at Hever Castle and Hide and Seek.

When Calderon was not at Hever Castle, he and the other members of this art colony were found painting and consorting in the St. John's Wood area of London. Calderon's home in St. John's Wood was called Iveston Lodge. The Clique members and contemporary artists Sir Lawrence Alma-Tadema and James Jacques Tissot lived in close proximity.

Calderon was the son of a Spanish Literature Professor at King's College, London. Perhaps this early exposure to literature and history inspired the artist to explore these themes in his paintings. Born in Poitiers, France, the young Calderon came to England with his family around age twelve. After a short stint as a student of Civil Engineering, Philip Calderon became an art student at the British Museum and the National Gallery and later a pupil of James Matthews Leigh in London and Francois Edouard Picot in Paris. By 1853 Calderon was a regular exhibitor at the Royal Academy and the British Institution. Throughout his painting career, Calderon enjoyed great critical and financial success. Paintings by Calderon are in the permanent collections of The Walker Art Gallery and the Tate Gallery.