by traffic-light-man on Wed May 04, 2011 2:56 pm
That picture there was the first style of ATE signals, with the fully removable porthole doors. The generation after this had a dual door lock that sat in between the aspects (so directly between red and amber and amber and green) and locked both the one above and one below the lock. Then, of course, the generation after this is the one with 2 locks per door, as per most people's signals.
The French marketed ATE/Plessey lanterns used the centre door locks too.
GO lettered lenses were banned by 1957 due to the fact green doesn't mean go.
Your signal there, Joe, looks incredibly good in the bare metalwork! Good catch.