You are probably right about your suppositions. Its not unheard of for systems like Eureka to have been fitted to tower roofs in the 50s.
I assume you are aware that there is a small museum and enthusiasts group there?
Might be worth trying to contact Rob Trumman at http://www.controltowers.co.uk/Site%20Map.htm , he’s very knowledgble and helpful.

Thanks, I live a mile from the Tower in question and a fairly frequent visitor and this query came from a Committee Member of The MHAS I will have a word with Rob