TheOneKEA wrote:

Nothing. In fac rumour has it that the white aspects are going to be
replaced with blue aspects, to match the blue aspects to be used on the
VLU signalling.

Buuut...If you do that, then they could be confused with lamps
associated with tripcock testers. Fun eh?

Article on signalling on the Central Line, penned by one Clive Feather:
http://www.davros.org/rail/signalling/articles/central.html

Cheers,

Barry