The deal with trains that I have observed involves a member of station staff and a ramp at both ends. No idea how this works if at an unstaffed station. Also presumably means you need to allow extra time to find a member of staff on station arrival. And then there's all the non-accessible stations (e.g. South Bermondsey & many/most of the stations on the various South London lines).

In dog news: my dog is a brindle Staff cross! See icon. We think some of her parentage is lurcher, and in fact there's probably a several of other things in there too.