Anne Neville and Edward of Lancaster

I've read in more than one historical novel that the dispensation for
the marriage of Anne Neville and Edward of Lancaster in 1470 was
obtained from the (Latin) Patriarch of Jerusalem. By this time,
Jerusalem had been in Muslim hands for nearly 300 years, so the
office of Patriarch was a purely nominal one, whose holders never
went near the place.

None of the reference books I have at hand mentions this - is there
any evidence? If so, who was the Patriarch of Jerusalem at the time?

Ann