Stu, thanks for that, the scope is an EdgeHD, I just did as you suggested, and true enough the glass was skewed off at a crazy angle. Now with bobs knobs all tight and with the glass visually flat, I have returned the secondary to the scope and had a look at an improvised artificial star (sun reflection off electricity insulator about a k way), and whilst there is now a recognisable image, a vast improvement on what was previously just a mass of mush, I still can’t distinguish the shadow of the secondary. I’m going to wait for night and see if a genuine star sheds a little more light on the issue.
GalaxyHunter