special type of bayonet fitting for their signal light bulbs (to discourage theft).
Apparently the bulbs have three locking pins on the base instead of the usual two. Not that there's probably any trouble with taking a needle file and obliterating the offending pin.
I'm not sure about the pin spacing on this special bulb, but the ones we were talking about above have the three pins spaced 120 degrees apart around the base. A normal BC bulb has its two pins opposite each other, so just filing one pin down wouldn't work.
I wonder how long this base has been used by London Transport?
Anyone else (probably from the U.K.!) remember seeing an old Arthur Askey movie where he's sleeping in the Underground station (as many did during WWII) and then opens up a signal lens at the end of the platform to run his electric shaver?
[This message has been edited by pauluk (edited 12-02-2002).]
