GEC Z8430CM Lantern Installations
The GEC Z8430CM was designed for 250W-400W MBF/U lamps, or in later-years, 250W-400W SON lamps. The CM version is not to be confused with a similar lantern, the Z8430 which possesses a Z6630 refractor bowl for MA/V lamps. The Z8430CM is fitted with a "corrected mercury" (MBF/U) refractor bowl.
Crewe
This example was spotted around the back of CeX in Crewe town centre. I had a chance-glance in that direction, which is when I had spotted it! Makes me wonder how much I've missed simply because I didn't look at the right time, but I prefer not to dwell on that!
The lantern still looks good for it's age, and may (although unlikely) still be operational, even in the event it's retrofitted! There are some smaller halogen floods installed around the courtyard, so it could also be defunct.