Here is the latest lantern in my collection:
It is a GEC Z9541 "Brick". You may be asking "What makes a Z9541 different to a Z9545?" The answer is I'm not fully sure, because I only knew of the existence of the Z9541 as a product code when I saw it badged this way on this lantern. Could it be because the spigot is of a different style? Everything else is much the same I believe.
Sotonsteve's Z9541 Brick has got me thinking. My own Z9555 and Z9565, 135 and 180W Bricks both have spigots like this:
Looking at my pictures of Bricks from Guildford to Colchester, and Heathrow to Maidenhead they all have the same spigots as mine.
However the Z9541 is different.
I can see the reason for it, by blending the spigot socket into the plate with a deeper web, the whole assembly is much stronger.
On the original design, there is an abrupt transition from the socket to the plate - but given its thickness I'm surprised it was considered a weak point. These lanterns are very light and 180W versions survived in Portsmouth for 40 years and the 1987 hurricane. Does anyone recall seeing a failed one?
Given the different designs it seems GEC weren't that happy with it..