query: SELECT ?person ?personLabel ?start ?end ?partyLabel ?constituency ?constituencyLabel {
    ?person wdt:P21 wd:Q6581072;
            p:P39 ?statement .
    ?statement ps:P39 wd:Q16707842 .
    OPTIONAL { ?statement pq:P580 ?start } .
    OPTIONAL { ?statement pq:P582 ?end } .
    OPTIONAL { ?statement pq:P768 ?constituency } .
    OPTIONAL { ?person wdt:P102 ?party } .
    SERVICE wikibase:label { bd:serviceParam wikibase:language "en" } .
  } ORDER BY ?personLabel