The motorbike\scooter license regime is now so very complicated. This was changed again on the 19th January 2013.The Vectrix was an expensive flop
I do like the look of the C-Evolution, and it would be a great bike for someone who didn't yet have a driving licence (it can be ridden with just a CBT from what I understand) but it is a little pricey. I think i'd take it over a twizy, though.
For the C-Evolution having a maximum of 11kW/14.6bhp (equivalent to a 125cc engine category), you need a provisional A1 motorbike license with CBT and L plates or a full A1 or greater license.
50cc Mopeds allow anyone with a full car driving license obtained before 1st Feb 2001 to ride without a CBT or L plates, after that then a CBT is required.
Current rules here