Hi Greg sounds like a real nice antique time-piece marked with British Hallmarks; UK marks are mostly 3-5 marks not always aligned in the same order.
The monarchs head is a duty mark, a female profile in a circle is a UK duty mark - Queen Victoria ca. 1838 -1890 - pocket watches were not only practical accessories but a popular Victorian fashion accessory (predominately male). Crown then 18 is for UK on 18ct Gold - ca 1798 - 1974. The letter B could be the date letter.
