Following on from my last post on H2 - HAA emplacement, Trimley, I also visited the site of the GCI (Ground Controlled Interceptor) Radar site at Trimley on the same day. I must admit I do not know that much about WW2 Radar so most of the details for this post come from Wickidpedia.
Chain Home Radar sites only picked up raiders as they came in over the sea. Once they had crossed the British Coast, tracking was entirely reliant on the Observer Corps. To improve on this situation, the RAF established a network of 'Ground Controlled Interceptor' Radar stations. These stations were able to direct search lights onto enemy raiders but more importantly vector night fighters to a close proximity of the raiders so they could be engaged. GCI was up and running from 1941 but I think the Trimley site was only operational from early 1943.
I presume the remains at Trimley toady are of the the main operational building plus some of the domestic huts.
One more post on the Trimley visit to come - as far as I know a unique 'Suffolk Square' Pillbox in that it has an AA well attached much the same as a Type 23 Pillbox.
Images 1- 11: Presumably the main Operations Building
Images 12-17: Remains of the Domestic site
Image 18: large concrete rubble remains
Image 19: Remains of the wire defence - barbed wire and screw pickets