Well, the repair might be as easy as thoroughly cleaning the joint, fluxing it, and heating it until the brass flows. That also might not work at all, in which case the repair entails removing the stays entirely (or at least removing the brake bridge), removing all of the old brass, and then rebrazing with new brass or silver. This probably won't affect the existing joinery (esp. if you use silver) but that depends upon your brazing skills, to some extent.
What caused it in the first place? Improper cleaning, inadequate heating, abuse...
I bet the second pic shows a repair. I'm no expert on Raleighs, but I'd have a hard time believing anything like that would make it out of a major shop like Raleigh once was.