Also known as the Maunsell army forts. Guy Maunsell designed forts for anti-aircraft defence. These were larger installations comprising seven interconnected steel platforms, five carried guns arranged in a semicircle around the control centre and accommodation while the seventh, set further out than the gun towers, was the searchlight tower.
Three forts were placed in the Mersey and three in the Thames estuary:
Red Sands (U6)
Shivering Sands (U7).
Each of these AA forts carried four QF 3.75 inch guns and two Bofors 40 mm guns. During the war the forts shot down 22 aircraft and about 30 flying bombs. They were decommissioned by the MoD in the late 1950s.
The days of Pirate Radio
Red Sands was occupied by Radio Invicta, later named KING Radio, before Ted Allbeury turned it into a professional-sounding easy listening station called Radio 390, after its wavelength of approximately 390 metres. The Danger Man episode "Not-so-Jolly Roger" was partly filmed at Redsands and includes an acknowledgement to Radio 390 in its closing credits. Also filmed at the Red Sand forts was the Doctor Who serial Fury from the Deep, in which the complex stood in for a North Sea gas refinery besieged by an intelligent seaweed creature.
The size of the Army forts made them ideal antenna platforms, since a large antenna could be based on the central tower and guyed from the surrounding towers.
Red Sands Radio broadcast in 2008 from Red Sand Towers to celebrate the 40th anniversary of pirate radio