Thanks for the response.
I have also found this which says twist and go is allowed – but only if from Jan 2016 there is ‘type approval’ of the bike. Has the Model 15 been type approved?
Power assistance – “Twist and Go” Because of the particular benefits for elderly and disabled users, pedal cycles providing electrical assistance without use of the pedals – usually called “Twist and Goes” – are included in the above GB classification provided they are capable of pedal operation and comply with the above restrictions on maximum motor power and assistance cut-off speed.
However, under European law5 new “Twist and Go” vehicles will, from January 2016, have to meet a range of technical requirements before they can be used on roads. This will normally be established by “type approval” at the manufacturing stage but importers and individuals will be able to seek an individual approval for vehicles that have not been type approved.