MB27 back in 1990, along with a 20 restriction board, some section switches and some very contentious 'wrong-side' monitors - especially back in the days before CSDE.
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I feel the need for a lengthy explanation!
Peter Langsdale 19:15, 19-03-2012
..sorry - MB27 = MB was the 'cabin' code for Metropolitan Line, Baker Strret - with 27 being the associated 'lever' it was once worked off (though by that time it was probably done from Baker Street Signal Control Centre). MB27 was the station starter at Baker St platform 4 and this picture is from a driver's perspective. The monitors at this location were 'wrong side' i.e. they were not the same side as the platform. When they were wrong side it more than doubled the risk of a driver opening or re-opening the doors on the wrong side. Eventually CSDE (Correct Side Door Enabling) was installed to prevent the possibility of that happneing but by the time it was installed most wrong side monitors were moved to the 'right' side. Due to the nature of platform 4 (it being close to the Circle platform) doors would often get held open making it a blackpsot with regards re-opening on the wrong side. (Hope that isn't TOO long an explanation)
T & Q 22:31, 19-03-2012
Thank you very much, T & Q, just enough explanation for my old, steam age brain to comprehend.