Type of permitted folding bikes on London trains & Tube? I have found quite a bit of information about taking folding bikes on trains and the Tube in London. Specifically it says you can take a folding bike pretty much anywhere.

However, having examined the small print of various train companies in the UK there is usually a distinction drawn between Bromptons and the rest, i.e. Bromptons, which obviously fold up really small, are considered "true" folding bikes while the other types of folders appear to inhabit some regulatory grey area, halfway between a folder and a non-folder.

I'm contemplating buying a Montague Crosstown. As you can see there, this has full-size wheels. Even if I wrap this in a bag I would anticipate getting some nasty looks if I take that on a busy-ish Tube / train in London, but I can cope with nasty looks.  Does anyone know what the actual regulations are?
Some UK rail companies, such as GWR (who operate some local trains in West London as well as mainline services) only consider bikes to be folding if the wheels are up to 20".


  Folding bikes with a maximum 20-inch wheel can be carried as luggage without any restriction. Please make sure you fold it before boarding.


That would exclude the bike you've pictured, unless you can pack it in a bag and call it luggage (checking the size of that too)