Okay, this is a bit of a long shot. 

One of my favourite lanterns which used to be in use outside the entrance door to my primary school - I started there in 94, and last time I drove past the place a few months back, is still there and working!

It's a GEC Nightwatch fixture - I'm 99% certain of that.  Opaque white diffuser, brown backing box, cuboid in shape.  Looks to be a bit longer than your typical F8T5 fluorescent fixture if my eyes are right.

What made this one interesting is that there are actually two lights in the box - on the left there's a SOX (I'm assuming 18W) lamp.  To the right however there's an incandescent - I'm guessing from the look of it, 60W - I guess to provide some instant light while the sodium lamp warms up.  I never realised that was even there for a while, though I found the unlit space at that end of the lantern a bit odd - until someone switched it on by accident one day and I discovered there was an incandescent there!

Has anyone got one of these - or has even seen one and has a clue what the model number etc is so I know what I'm looking for.

Just a little bit of nostalgia for me there, so I'd really like to pick one up if I can get hold of one.