Recessed Crompton Contrast T12 fluorescent fitting

This is at a less-used block in my college, lit purely by these recessed Crompton fittings! I think some actually have T12 lamps in, others T8. The diffusers are hanging and yellowed on most examples. Besides these, the lighting in my (huge) college is quite recent, besides: A rarely-used hall lit with Atlas Superslims (lovely!), a grey-sided Atlas PP in a store-room, one twin 65w Thorn PP with a reflector plate, and a corridor lit by some interesting Thorn fittings with diffusers from the early 1990s.