I have the combined Roundheads and Cavaliers also on double vinyl.They are both interesting,though ive always leant in a Roundhead direction....I bought that LP back in the 1970s (?) and loved it, but I couldn't quite figure out the tunes listed on the label and in the jacket with what I was hearing.
Thirty years later, I bought a newly issued 2-CD set of Cavaliers and Roundheads, being this and a companion release by St. George's Canzona. All became clear when I played the CDs.
My LP was of the Roundheads' songs, but labeled and packaged rather 'cavalierly'.