Purple? aspect at Earl's court

You are indeed spot on

As a bit of added detail may I refer you to my page at www.trainweb.org/districtdave/html/earls_court.html which goes into some detail - including some stuff about the tripcock testing equipment.

The westbound platforms are indeed longer - the stairs from the platform to the booking hall at the Earls Court Road (east) end of the station were further back than they are now. The stairs at the Warwick Road (west) end have to be level on account of the 'over bridge' at that end of the station.

As Colin has said you are spot on but remember that even though it may appear purple or blue it is actually a lunar white aspect!

My understanding is any one of the three, depending on the lens fitted - though more modern ones all seem to have used lunar white.

its proberly done on wotever lense they could find first in the stores

All I can say is that in my days in signals they were never referred to as anything but luinar white aspects. Having said that some of the lenses are clearly blue when not illuminated, indeed they are blue glass but with the correct bulb behind them glow white when illuminated. I am not so sure about the purple lenses as I have never had one in my hand but my belief has always been that they were plain glass painted purple to give a 'lunar' hue to a plain white light, most of those I saw appeared to have lost the purple tint at the centre of the lens perhaps due to heat of illumination over many years of operation.

Of course it may simply be that my knowledge of the subject is not as full as it might be.

If SE099 is the spec I think it is, then those signs were used for all sorts of things, including Route Secure and Rear Cab Clear Visuals, as well as internally illuminated PSR signs. If so, they were the purple ones, Baker Street (B'loo) being one example of them.