Complex sentence: At the time of the abdication, there was controversy as to how the ex-King should be titled--other possibilities were the Dukedoms of Cambridge or Connaught, though neither was likely because the Marquessate of Cambridge and the Dukedom of Connaught were both extant at the time.
Split into simpler sentences: At the time of the abdication, there was controversy as to how the ex-King should be titled: other possibilities were the Dukedoms of Cambridge or Connaught. Neither was likely, because the Marquessate of Cambridge and the Dukedom of Connaught were both extant at the time.