In 1870-72, John Marius Wilson's Imperial Gazetteer of England and Wales described Calshot like this:
CALSHOT-CASTLE, an extra-parochial tract in New Forest district, Hants; at the W side of the mouth of Southampton water, 7 miles SSE of Southampton. Pop., 23. Houses, 6. A castle here was one of the numerous small forts built by Henry VIII., for protecting the south coast; and is now a dwelling house.A lighthouse is here, with a fixed light, bright and red; and a light-vessel, called the Calshot Spit light, is in the neighbourhood; with a minute revolving light. Calshot-Castle is also a coastguard station.
GB Historical GIS / University of Portsmouth, History of Calshot, in New Forest and Hampshire | Map and description, A Vision of Britain through Time.
Date accessed: 30th March 2017
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