Had a reply from Shaws, Techs have looked at the vid and say absolutely normal for floating discs.
Only had floaters on two other bikes, my last Fatboy (Ferodo parts) and a Trumph Rocket III. Thinking back they had more of a 'click' than a 'clonk' though.
To be honest this only occurs after I’ve had to hold the bike from rolling back at an uphill stop. The floating disc rotor moves in opposite rotation to normal and shifts against the other side of the rivets. Hence the first time the brake is applied going forward –' clonk'.