Horsea Island

Horsea Island was an island located off the northern shore of Portsmouth Harbour, England; gradually subsumed by reclamation, it is now connected to the mainland. Horsea falls within the city of Portsmouth and was wholly owned by the Ministry of Defence as part of the HMS Excellent shore establishment, which maintains its headquarters on Whale Island.

However, in 2013 the south-eastern corner was acquired by Portsmouth City Council for housing development.[1] Most of the area to the south-west of the lake is part of the Portsmouth Harbour Site of Special Scientific Interest (SSSI), the remainder was declared a Site of Importance for Nature Conservation (SINC) in 2011.

Horsea was originally two islands, Great and Little Horsea, the former large enough to support a dairy farm.

In 1804 a Royal Powder Works was established on Little Horsea in connection with the gunpowder magazine at nearby Tipner; by 1849, however, it was no longer in operation, and no above-ground evidence of the site remains to be seen.

The islands were joined to form a torpedo testing lake in 1889, using chalk excavated from Portsdown Hill, 1 km to the north, by convict labour. A narrow-gauge railway was constructed on the site by the army to distribute the chalk. Although the lake length was increased from 800 yards (730 m) to over 1,000 yards (910 m) in 1905, rapid advances in torpedo design and range had made it all but obsolete by World War I.

In 1909, the island became the site of one of the Navy's three high-power shore wireless stations, which saw it populated with dozens of tall masts. In the 1950s the lake was used in the testing of improved Martin-Baker Ejection Seats, following catapult launch mishaps on carriers in which Fleet Air Arm aircrew often sustained serious compression injuries to the spine after ejecting from submerged aircraft.

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