Many thanks for the reminder of the Decca 424, known in the RAF as the ACR 7D, on which I performed 3rd line servicing throughout most of the 1960s, while I was based at RAF North Luffenham.
For geeks like myself, here is a very thorough article describing this equipment and its use:
decco type | decca type | airfield radar | 1953 | 1232 | Flight Archive