Hi, I had to strengthen the bonnet to stop the mirrors vibrating.
Using a piece of flat bar for each side, I bent it to the curve of the bonnet, then fixed it in place using 1 mirror bolt, 1 bolt through the rear bonnet catch (i.e. at the bottom return edge of the bonnet) and liberal use of Araldite.
One year on and it's still in place.
If you're at Newark, look me up. (Blue 2b, F reg, tall screen)
Nick