But > [But that]
5 Tidings thereof, and so them still debarred.
still > continually debarred > kept out, thwarted
6 It was a famous present for a prince, 7 And worthy work of infinite reward,
reward > regard, heed; hence: merit
8 That treasons could bewray, and foes convince;
bewray > betray, reveal convince > overcome, vanquish; convict
9 Happy this realm, had it remained ever since.
Happy > Fortunate; happy
302.22