Took me ages to get one of these as Surrey didn't used them, it was Beta 5 territory here

These seem pretty bad for moisture ingress and corrosion in my experience. They should have had a gland on the cable entry.

Love the style of the MIs, but the very first time I ever got to see into one, I was quite surprised how that hot running ballast was crammed into the side of the canopy, and how it burned everything a heavy brown colour! These would have been better remote geared?

They did do them remote geared for a time, but eventually remote gear lanterns fell out of fashion.