Drill holes in either side of the front mudguard/fender, and mount it under the headlamp.
On full bump, it will rise up and smash the headlamp, and trash the numberplate.
On non-british bikes, you'd ditch those strange looking brackets, and fit it ALONG the top of the mudguard.
So would smarter-than-average british owners too !!
Vincent owners fit them ABOVE the headlamp, so it becomes a mini flyscreen/bug deflector.........
What ye fit it to though ?