It's not exactly that the back button doesn't work. It's because for some reason they seem to be redirecting in some weird non-HTTP way from their `.co.uk` doma

It's not exactly that the back button doesn't work. It's because for some reason they seem to be redirecting in some weird non-HTTP way from their `.co.uk` domain to their `.com`, even though you already got a complete `200` response from `.co.uk`. As a result, clicking the back button only once from the `.com` takes you to the `.co.uk`, which redirects you back to the `.com`. Clicking twice, or if you follow the `.com` link in the first place, does not affect the back button in any way.