what is the least tonnage grt when the nationality is british and the ship is kidalton?
CREATE TABLE "table" (
  "date" text,
  "ship" text,
  "type" text,
  "nationality" text,
  "tonnage_grt" real,
  "fate" text
);
SELECT MIN("tonnage_grt") FROM "table" WHERE "nationality"='british' AND "ship"='kidalton';