Gotta say that Nellie the Elephant is probably one of the least offensive of those novelty records. It's not up there with Mr Blobby and anything by Black Lace. It's one of those songs that as a kid was a bit more anarchistic and rebellious in tone. You could scream the lyrics rather than sing them.
Best novelty records? Hole in my Shoe by Neil off the Young Ones, Star Trekkin' and The Bucket of Water Song.
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I have to say that it's a shame that Cop missed out on Tiswas, him being one of the youngest members of the team. He'd have appreciated it's pure anarchy.