Byzantium was only active for a brief period at the tail end of the late 1960s and the first half of the 1970s, but the band is still well-remembered within the British underground rock scene.  Now, the group’s officially issued works (and more!) have been collected by Cherry Red’s Grapefruit imprint on the new 5-CD set Halfway Dreaming: Anthology 1969-75. Byzantium emerged from the ashes of the band Ora, formed by students Robin Sylvester, Julian Diggle, and Jamie Rubinstein at University College School in Hampstead.  After releasing one album with which Rubinstein…