Thanks for replies. It was some consulation that on my Roadster at least the bonnet did not go flying over my head but just waved gently up and down, suggesting tbe louvres equalise wind pressure on upper and lower surfaces.
All four springs on the releases are very strong. I'm sure its just a catch adjustment issue which will be sorted today.
I did check on a variety of Classics parked outside the dealers a couple of weeks ago and three out of five had some play in the front bonnet fixing on one side or the other, similar to that on mine!
I note that relatively few Classics have a bonnet strap as new or fitted later. Shied away from ordering one on new build due to potential scuffing of bonnet paint not to mention being a little too retro for me. How bad is the scuffing issue?