Welcome to TM Roger.
In all honesty I don’t have any clonk. I do however have a ratttle from the engine somewhere under hard acceleration. Not too concerned but just aware when I’m pushing it above 4/5000 rpm particularly that it sounds a bit like a screw is a bit loose somewhere under the bonnet….
Hope your clonk gets sorted old chap
HB
I had an annoying rattle and discovered it to be the bonnet stay. Some strategically placed pieces of rubber sorted that out.