I have a rather large head and face, most glasses I have tried don't fit or the lenses look stupidly small against my head, does anyone know of any shades that are suitable for the man with a generous head size?

Same problem here. I have to stretch the arms apart to fit. Plus I have a broken nose and the bridge is tiny, so most just end up keeping the sun off my cheeks.
Briko, PBK and most cheapos don't fit.
I might try Oakley Jawbones, lots of dosh though.

Adidas do large sized frames.

Gold Fish Bowl

Similar problem here – except a chunky bridge on my nose means sun burnt cheeks but well protected eyebrows! 😯

I've a large head and found that Oakley Jawbones are the best fit – close enough across the bridge of the nose and to my cheekbones that dirt / insects etc don't get into my eyes. They're also pretty wide. I prefer the swappable lenses system to that of the Half Jackets or Radars – much easier. My commute starts in the dark so I swap out hi-res yellows for iridiums on the train – they've held up well to daily use for the past 9 months or so.

That said, XLJ (sp?) Half jackets weren't too bad. Certainly not as expensive as the Jawbones.