Sandys is best known today as a member of the Pre Raphaelite circle who specialised in highly finished portrait drawings, either in coloured chalks or oils. He also executed fine woodcuts and produced many illustrations for The Cornhill, Once a Week, Good Words and The Argosy among other magazines, as well as illustrating poems for Swinburne and Christina Rossetti.
Sandys was the son of a portrait painter and drawing master, and his talent was recognised early on by the Rev. Mr. Bulwer, Rector of Stody, a keen amateur artist and a pupil of Cotman. With encouragement from Bulwer and his family, Sandys obtained a place at one of the new Government Schools of Design, where he copied from casts and copies, flowers, foliage and architecture. Sandys also exhibited his work in the annual exhibitions of the Art Union, the earliest exhibit being in 1839 when he was ten. His skill won him much acclaim locally and some professional work so before he arrived in London he had already executed drawings of professional quality for both the Antiquities of Norwich and The Birds of Norfolk.
Sandys drawings of The Birds of Norfolk were commissioned by John Henry Gurney, the Norwich banker, with a view to using them as the basis for his book on the subject, published circa 1844. The Gurneys were patrons to a number of artists of the Norwich School.
In London Sandys studied at the RA Schools under George Richmond and Samuel Lawrence (who taught him to draw in chalks)