exactly, but victories in the battlefield do, as Henry proved.
of course there is the argument that Perkin must have presented some sort of percieved legitimate claim to the English throne for all of rest of the royal houses of Europe to have accepted his presence in their courts, and in some cases given his invasion of Ireland material support. If Perkin were a total fraud, as he confessed he was later, it would seem that the French, the Spanish and the Imperial courts would have shied away from him.
at any rate, the Perkin Warbeck saga makes an excellent story.