Thanks guys for your replies.
I removed the freecam v1.1 and the problem disappeared.
After looking at the latest updates, I found that a v1.2 for the freecam is now available which is for GWX and which removes the periscope issues.
After installing it with olc gold (less the enhanced damage effects old file), I still had the same problem, and so it is certainly the freecam that is causing the problem.
However, I then removed OLC gold, installed the v1.2 freecam and the problem is gone, whilst the freecam works fine.
I can therefore only assume that the freecam (even v1.2 for GWX), is not compatible with olc gold.
@ olc- is there any easy cure for this do you think as I really dont want to have to do without your wonderful mod, but really want the freecam mod too!
Many thanks
Rob