An unidentified sitter

[A pencilled inscription verso in a modern hand — presumably transcribing an inscription from an album page — identifies the sitter as 'Miss Ellis / later Mrs Cave.' The only marriage that I can find matching these surnames was between John Halliday Cave of the Royal Navy and Miss Louisa Ellis. The couple appear on the 1871 census living at Henbury Court in Gloucestershire, which certainly looks like the residence of a Silvy sitter — a governess, a butler, a footman and seven other servants — but since this couple were married in 1859 before Silvy opened his studio, this Mrs Cave can't be the woman described as 'Miss Ellis / later Mrs Cave' on the back of a portrait by Silvy.]