Thanks Brian,
Most interesting.
I certainly remember the "H" s from my earlier days, but not the others.
Possibly because we didn't live in Central London.
A lot of the civil defence ones stayed in use through to mid 1960's ( due to cold war)
Dad was a firefighter through this time, the sirens were still in use in 1970's to call out part time firefighters.
Ttfn
Pete
An Elephant is a Mouse designed to
a government specification.