Type of permitted folding bikes on London trains & Tube?
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)