Fort Grey, colloquially known as the "cup and saucer", is a Martello tower located on a tidal rock in Rocquaine Bay in Saint Peter, Guernsey on the west coast of the island.
Wikipedia https://en.wikipedia.org/wiki/Fort_Grey
Official Website http://www.museums.gov.gg/article/101090/Fort-Grey
Address GY7 9, United Kingdom
Coordinates 49°26'21.336" N -2°39'18.062" E