CREATE TABLE table_30965 ("Episode" FLOAT, "Broadcast date" TEXT, "Guest ( s ) " TEXT, "Singer ( s ) " TEXT, "Ratings" TEXT)

when was the episode on which barbara windsor and heston blumenthal guest starred broadcasted
SELECT "Broadcast date" FROM table_30965 WHERE "Guest(s)" = 'Barbara Windsor and Heston Blumenthal'
SELECT "Broadcast date" FROM "table_30965" WHERE "Guest(s)" = 'Barbara Windsor and Heston Blumenthal'