What is {position held} of {William Cavendish-Bentinck, 3rd Duke of Portland} that is {start time} is {1807-3-31} ?
What position did William Cavendish-Bentinck, 3rd Duke of Portland hold on March, 31 1807?
SELECT ?obj WHERE { wd:Q157208 p:P39 ?s . ?s ps:P39 ?obj . ?s pq:P580 ?x filter(contains(YEAR(?x),'1807')) }
select distinct ?obj  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q157208> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P39> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> ?obj .
?statement <http://www.wikidata.org/entity/P580> <1807-3-31>
} 

On March 31, 1807 what positin did the 3rd Duke of Portland hold, Duke William Cavendish-Bentinck?