The earliest edit listed for Sir Arthur Sullivan is from 2005: it created a ‘collaborated on’ credit with Gilbert & Sullivan, but that G&S entity has since been removed. Now the only Gilbert & Sullivan entry I can find in the database is this threadbare entry which was created in April 2018. Neither Sir Arthur Sullivan nor Sir William Gilbert has a ‘Gilbert & Sullivan’ relationship. What happened?
I checked the Wikidata element for an older MBID, but I found no MBIDs in its editing history.