Right guys (and any interested ladies of course)
Firstly my sincere thanks to all who have contributed replys.
Here is the full SP for anyone who wants to be able to fold their mirrors in and cant at the moment.
I've tried to get the glass out to get to the hinge and as far as I can see the backing plastic to it has 'lugs' which must be clicked into place before the glass is stuck to it.
In other words if you t ry and remove it, it is likely that either the glass will shatter or the lugs will snap off of the backing plastic base plate.
So sadly thats not an option unless the glass is already broken.
The 'join' where the mirror should hinge is very 'snug' but as you'll see if you've looked its going to be easy for water to run into it.
So I started with the small mirror as it should have less chance of flexing and breaking the glass.
So, as was suggested I tried lubricating it with WD40.
Then taking hold with both hands to cut down on flexing (as though you were holding the mirror to look into it) and so you can push and pull so you can keep most of the strain on the pivot of the hinge and not transfer it onto the door completely, I tried a firm 'wobble' then a good go at folding it in and it moved!!
ONLY A BIT AT FIRST.
And there was some ugly grinding noises.
The
problem is then visible! The mounts are aluminium and the close fitting alu' has oxidised and seized.
Get more oil into it and wiggle it until the join frees up.
Hopefully by now the WD40 has started its magic on the large one too!
Remember the whiteish alu oxidisation will quickly bnreak down once you get it moving so the hinge will feel completely different once its been moved a few times.
Problem solved!
Cheers everyone