Until Mr Plod spots you using it on the public highway. If it's too fast/heavy/powerful to qualify as an EAPC, it's a motorcycle subject to all the usual construction and use, tax, testing and licensing regime you'd enjoy if it had an internal combustion engine.
I'm not disagreeing with you, I'm suggesting the likelihood of someone getting caught unless they're in an accident or cruise past a police car doing 30mph without pedalling and an obvious motor on their bike is pretty low. In my opinion.
Until Mr Plod spots you using it on the public highway. If it's too fast/heavy/powerful to qualify as an EAPC, it's a motorcycle subject to all the usual construction and use, tax, testing and licensing regime you'd enjoy if it had an internal combustion engine.