The Portland CEW ROTOR Bunker was constructed during 1950, 1951 by the contractor Robert McAlpine. Fit out was started by the GPO (General Post Office) that same year and the radar station became operational in 1953. The above ground guardhouse was constructed from Portland Stone, making it different from other ROTOR Stations around the country. The below ground level at Portland was also unique as it was accessed by a lift shaft, rather than a sloped shaft, and was the deepest at 70 feet.
The station was equipped with the latest stage one RADAR equipment, including Type 13 and Type 14 RADARS and an American AN/FPS Type 3 stop gap RADAR. This was replaced by a type 10/IFF in 1954, making the station fully equipped to start fighter interceptor trials. With the advent of the Type 80 Garlic Green radar, and the reduction of the overall system, Portland was one of three bunkers that were not chosen for upgrade. In April 1956 the AN/FPS Mk3 was removed and three months later the type 13 & 14 radars were dismantled. With this, the station was declared in a low state of readiness. By 1958 the station was reduced to care and maintenance, and in the same year, reduced to non-operational.
The site was taken over by the US Air Force who set about building a microwave relay station for the Troposcatter cross-channel relay link at Ringstead. They did not utilise the underground bunker, and in 1969 whilst the US occupied the site, the fire occurred there.
In 2001 the Ministry of Defence put the site up for sale and shortly before the sale set about stripping the lift and access stairs from the building. Access was replaced with a caged ladder transcending the 70ft shaft. Now a children’s farm occupies the above ground and the below ground areas are in an extreme state of dereliction.