Tried again this evening at Bouverie St this time, red light again and information station “sorry, unable to service your request” etc. Got home (after another 20 min walk to Waterloo), check the online TfL account and another quid subscription logged! So, five unsuccessful attempts to access a bike today, all of them have reached the TfL main server and each one has triggered a £1 subscription charge.
Just how screwed up is this system! Will phone TfL later and attempt to sort it out.