Thanks all for the tips, the currently exposed surfaces don't see to suffer to much. I am going to strip the existing material and use it for a winter. I have covers for the toys inside and see the extent of the problem over the winter and apply an insulating covering the following summer.
I have a large (maybe 4 metres, 12 feet in diameter) metal dome which is in need of some refurbishment. Does anyone have any particular advice about what to cover the interior with? Previously there was some polystyrene panels fixed up with wallpaper glue which over time have broken off and land on my optics and equipment, something I'm not very happy about. Take a look a the video or pictures in the instagram for what has happened over time (https://www.instagram.com/rhulobservatory) Is there any particular need to cover the interior at all? Thanks, Stewart