Mr Benn was a cartoon character - a little man in a suit and bowler hat - who in every episode would go into a magic clothing shop, try on a costume - cowboy, deep sea diver etc - and then become that person, and have an adventure. There were only a relatively few episodes made, but they became a minor cult classic.
I hadn't thought of them in connection with spanking, but I can see the possibilities; get some deserving young woman/women (maybe on their way to a fancy-dress, Halloween, or hen party) to try on costumes - schoolgirl, Victorian maid, harem girl, air stewardess etc (a quick Google search for 'sexy Halloween costumes would doubtless turn up dozens of options). Then they find that they're trapped into playing the role - and getting the spankings that go with it! It could be the basis of a long story, or with multiple spankees, an entire series! | 
