Which polling institute showed a lead of 12% and a Labour share of the poll at 40.2%?
CREATE TABLE "opinion_polls" (
  "date_s_released" text,
  "polling_institute" text,
  "nationalist" text,
  "labour" text,
  "democratic_alternative" text,
  "undecided_no_answer" text,
  "lead" text
);
SELECT "polling_institute" FROM "opinion_polls" WHERE "lead"='12%' AND "labour"='40.2%';