See picture below, has suction pad that sticks to window then I believe when you flip the for hire sign down it lights up. Not tested as been sitting in the garage for years. Believe it did work when I purchased it.
£20
Coleman Traveller 4000 heater
Come with case, handbook and a random very old set of matches. Also has previous owners name and address etched on the back.
£35 - Collection from Hertfordshire or postage at cost.