I suppose you can never have too many radar heads, provided they compliment, rather than cause grief with, each other. Glasgow once had a pair of Marconi 264s and Leeds Bradford kept the ACR430 going for several years after the Watchman was commissioned. It will be interesting to see if LBA plumps for its own SSR aerial when the Watchman is replaced, which can't be too long away.
A thought has just occurred to me. Are radar towers meant to be frangible or not ? It might depend on proximity to runways, protected bits and so on.