Mudguards

I would rotate that rear fender so that you can attach it to the strut behind the BB, whether it's drilled or use a clamp around the bar. Up top, a simple "L" bracket hung off the brake bolt makes a much more stable and rattle free attachment.

That's what I was going to do but it won't fit in there, guard is too wide. And actually that brake bracket fits super tight as you bend the little fingers round the inner arch, it's solid, won't move and doesn't rattle. It's completely silent now, no rattles at all! Arches are very good quality, I would recommend them!