When I expressed some doubts about this proposal, my husband said that it was not something initiated by JC but was one of a number of suggestions made when JC asked for people to put forward their ideas.
If it turns out, as the I reports today, that JC is going to propose it in a speech today, then I don't think it's a very practical idea. Having used the tube to get to work during rush hour periods, for 20 years or so, it is a bit of a scrum to get in any carriage at all. As others have said, who would monitor it - it would surely require an increase in platform staff and at the moment station staff are being laid off. But perhaps I'm being too negative - apparently Japan, India and Russia already have such a system.
In a sense it disempowers women and ideally one would hope that all men could behave like civilised human beings. That would, however, require a change of global culture where girls and women are valued as much as men, where they are not religiously and culturally depicted as "temptresses" and where their sexuality is not used to market products and services.That's not going to happen overnight and solutions are needed now.
I wonder if more training could be given to girls and young women on assertive behaviour. It is said that sex attackers are more likely to attack women whose body language and general demeanour appears nervous and unconfident. Perhaps more awareness of strategies that a woman might use to assist in keeping her safe might also be useful - though it seems wrong to me that this requires a woman to be constantly on guard and almost entirely responsible for maintaining her own safety.