As part of the preparatory works for the lengthening of platforms 1-4 at Waterloo, a new gantry has been erected across the ends of platforms 1-8. On platform 8, this gantry carries a new signal - already in use - about a coach length in from the platform end (ie, towards the concourse), so that the front of a 10-coach (444) or 12-coach (450) train is beyond it. This signal is numbered W15. At the very end of the platform, the original 'starting' signal is still in use, now numbered W15CA. I understand the CA suffix to indicate 'co-actor', but if this is the case aren't these signals the wrong way round? Shouldn't the 'main' signal be right at the end of the platform, with the co-actor further back, perhaps for easier sighting from shorter trains?