Ninjas are very bad, or at least that's the BBFC's view. When the marketing wave pushed the Teenage Mutant Ninja Turtles over to Britain, the censors were quite clear in what would have to go.
The title couldn't be so obviously pro-ninja. The Teenage Mutant Hero Turtles were born.
The theme tune clearly would have to be changed, not only to refer to the new name, but to get rid of the reference about Splinter teaching them to be ninja teens. 'Splinter taught them to be fighting teens' was clearly more acceptable.
Another cause for annoyance was the fact the turtles were kitted out with ninja weapons. The swords, staff and forks were well known already to British audiences. The turtles, however, also carried a sinister form of arms clearly linked to ninjas.
Everybody knew Michealangelo carried nunchaku although curiously they were never used. Leonardo never slices people open, but the katanas did get occasional use, as did Donatello's and Raphael's weapons. The nunchaku became solely an item of the action-figure world.
Despite all of this, the Turtles were a phenomenal success in Britain, perhaps the biggest up to that point. And children still pretended to be ninjas...