Malcolm, Thanks for the tip re Halfords "Get you out of jail" cover in the absence of a fitted cover. It would be a handy back up.
John From "Storm Covers" has be in contact this afternoon and because I have a fully louvered bonnet is modifying the cover to extend it 10 inches over heating air intact that will stop water ending up in the trinket tray.
He will be shipping on Tuesday / Wednesday that's what I call service. Thanks to you all once again for your input.