This site is identified as Slough War Signal Station on the 3rd Edition OS Map as a small rectangular building and a probable mast within a rectangular enclosure.

The wireless telegraph building is close to Slough Fort which is described within the defence schemes of 1906 and 1914 as a Port War Signal Station but the listing of vulnerable points for 1917/18 lists it as 'Wireless Telegraph Station, Naval, Special'. The signal station is served by approach and fire trenches within a protective enclosure of barbed wire. The site of the signal station on the map is roughly that of the modern Coastguard station, a small structure with a 'bay' observation window. (1)

This feature is recorded in the English Heritage Historic Area Assessment for Allhallows Parish. The report states: "The remoteness of Avery and its proximity to the Thames and the Yantlet Creek provided ideal conditions for smuggling. This led to the establishment of a coastguard station here, presumably occupying a moored hulk on the riverside. This was swept away in 1897 and the station was reestablished in Avery, presumably in the building now known as Coastguard Cottage to the north of Avery House which also housed a port signal station….
Another component of the defensive system at Slough was the Thames Port War Signal Station. This was housed by the early 20th century in a building known today as Coastguards Cottage. Its purpose was to communicate with shipping entering and leaving the Thames via a wireless telegraph and visual signalling. Developed by the Admiralty at the end of the 19th century and operated by coastguards (also then under Admiralty control), the station ensured that no hostile or suspect shipping could pass the guns at Fort Slough unchallenged…To the north of the [fort] park entrance is Coastguard Cottage. The single-storey white-painted brick structures resembles neither a typical coastguard station nor a port war signal station - its previous functions - but the treatement of the tall machicolated parapet on its west wing has a military quality". "An unusual survival" (2)

Oxford Archaeological South, 2016, First World War Wireless Stations in England. (Bibliographic reference). SKE31551.

<2> historic england, 2014, Hoo Peninsula Outline Historic Area Assessment: Allhallows Parish. Research Report 11-2014 (Bibliographic reference). SKE31596.