query: # members of the 1922-23 Parliament - 615 members.
  SELECT DISTINCT ?item ?itemLabel ?constituencyLabel ?partyLabel ?start ?electionLabel ?end ?causeLabel {
   ?item p:P39 ?positionStatement .
   ?positionStatement ps:P39 wd:Q41582584 . 
   OPTIONAL { ?positionStatement pq:P768 ?constituency . }
   OPTIONAL { ?positionStatement pq:P4100|pq:P102 ?party . }
   OPTIONAL { ?positionStatement pq:P580 ?start . }
   OPTIONAL { ?positionStatement pq:P2715 ?election . }
   OPTIONAL { ?positionStatement pq:P582 ?end . }
   OPTIONAL { ?positionStatement pq:P1534 ?cause . }
   SERVICE wikibase:label { bd:serviceParam wikibase:language 'en' }
  }
  ORDER BY ?start