But the very success of the House of York was a more fatal blow to the trust in them.

It was by the act of the Houses that the Lancastrian line had been raised to the throne.
Its title was a Parliamentary title.

Its existence was in fact a contention that the will of Parliament could override the claims of blood in the succession to the throne.

With all this the civil war dealt roughly and decisively.

The Parliamentary line was driven from the throne.