I see a couple of regular electric assist cyclists in Hyde Park. One older gent has 5 different electric bikes, including that lovely Gocycle design. It looks so beautiful and classy. He also has another one with very chunky tyres, almost those of a scooter, and the whole thing looks like a bicycle crossed with a motorcycle.
There's a different rider with this same model of bike, and I'm sure his is illegally modified as he often comes through at 20mph plus.