CREATE TABLE table_204_223 (id DECIMAL, "party" TEXT, "previous council" DECIMAL, "staying councillors" DECIMAL, "seats up for election" DECIMAL, "election result" DECIMAL, "new council" DECIMAL)

which party had the greatest number of new seats in this election ?
SELECT "party" FROM table_204_223 ORDER BY "new council" DESC LIMIT 1
SELECT "party" FROM "table_204_223" ORDER BY "new council" DESC NULLS LAST LIMIT 1