"An Anthology of English Medieval and Renaissance Vocal Music" by "Noah Greenberg" ISBN 0 393 00461 9 Pub. Norton Library 1968 has about the first third or so within your time frame. The other stuff fits and sounds right too, it's just a little later.
The same book was published earlier (1961 & 1963) as "An English Song Book" by "Doubleday / Anchor" no ISBN, a friend of mine picked it up for $2 Can.
Good Luck JohnB