Mine has to be GECs, Z9517, we had loads of linear sodium lamps when I was growing up, and starting to take an interest in lighting, (at about 8), but we only ever had 2 types of lantern, Thorns Alpha Five, and in a larger number, the Z9517.
At the time I had no clue as to who made them, or what they were called, but I always found the Z9517 as smart and slimline for their age, and back in the 70s and 80s, (before loosing them in the mid 80s to MA 50s), they looked really smart on their outreach arms.
However it wasn`t until a few years ago I could identify them, it was only on Simons excellent Street lighting UK site, I identified it, I never found it in any collection, or anywhere on the internet, until I joined here, and found member David`s example!, these have to be one of the rarest lantern now to own, (in fact I don`t even think theres a hand full of them anywhere in this country), so David has a real gem there.
I asked my street lighting engineer friend, Steve, (who took our Z9517s down whilst working for contractor David Liningtons in about 1985), he says, the last he remembers, they were all loaded in a Transit van, and taken to the Cheshire Highways depot skips in Chester
.
I so wish I could go back in time to that day, and save as many as I could, as Steve would have put some on his truck, that he kept at his house back then.