Complex sentence: Abbots and priors lost their seats in the House of Lords; only archbishops and bishops remained.Consequently, the Lords Spiritual--as members of the clergy with seats in the House of Lords were known--were for the first time outnumbered by the Lords Temporal.
Split into simpler sentences: Abbots and priors lost their seats in the House of Lords; only archbishops and bishops came to comprise the ecclesiastical element of the body. The Lords Spiritual, as members of the clergy with seats in the House of Lords were known, were for the first time outnumbered by the Lords Temporal.