In reply to nathan79:
ESN was used as a not necessarily racist insult in the 60s and 70s, in the vein of "eppo", "spastic" or "cretin" (apologies for the use of these words as insults but I was at school in rather a sport worshipping toxic bully-rich environment in the early 70s - there were some very unpleasant people around and na doot they have done well out of it)
Post edited at 16:42