Thorn KSP London Line Open

This 'wafer thin' fitting was made as part of a modernist range of fluorescent fittings from Thorn. It was designed so the top part of the fitting would be invisible from all angles. These highly unusual fittings were never that popular, and to date i have never seen another example.
Ive had this fitting now for about 4 years, and its absolutely shot diffuser shows the many hours of use the fitting has achieved since first being installed in 1974. Here the fitting is open, revealing its tubes and gear channel. I will restore this when I can find (or replicate) another diffuser. If anyone can help me in the meantime, I would be extremely grateful.