Who remembers the Gilfillan MPN11/CPN4? You sat in a darkened truck in the middle of the airfield surrounded by whining magnetrons and oscillators, chinagraph in one hand, screwdriver in the other for adjusting cursors, MTI gain etc. Magic atmosphere.
And Bomber Command's CPN 18 in the '60's. Had a 40 mile normal range, but you could select '40D' (40 miles plus delay) which gave you a picture from 13 to 53 miles. The first 13 miles was sucked down the hole in the middle, so to speak, which left some weird distortions inside about 30 miles.
The Type 80, with pinhead-sized blips you could hardly see. You could go for a roundabout ride in the signal processing cabin, which was suspended directly underneath the radar head and rotated with it at 4 rpm.
Someone has already mentioned the ex-Bloodhound missile control radars converted for ATC use at Northern, Eastern and Midland Radars. Lovely piece of kit, with its built-in height finder and target tracking system, but very labour-intensive, needing a tracker and height finder for each console. Pity Midland Radar had such a large overhead they couldn't see anything.
Hatfield used to have a Marconi 232 and a 430. When the 232 died they arranged a microwave feed from West Drayton. One of the engineers (who was permanently out of his brains) devised a system for superimposing the 430 onto the WD picture, so we had a digital 430!