[{"attributes":[{"dept":"accounts","location":"onshore"},{"dept":"HR","location":"offshore"},{"dept":"technology","location":"NL"}]},{"attributes":[{"dept":"accounts","location":"onshore"},{"dept":"technology","location":"London"}]},{"attributes":[{"dept":"accounts","location":"onshore"},{"dept":"HR","location":"London"}]}]

db.collection.find({"$or":[{"attributes":{$not:{"$elemMatch":{dept:"technology"}}}},{"attributes":{"$elemMatch":{dept:"technology",location:{$ne:"London"}}}}]})