I'm not (quite) old enough to remember Love Thy Neighbour although I did see the spin-off film when it was somewhat improbably repeated a few years ago. I did wonder what the difference was between that and, say, Till Death Do Us Part, where Alf Garnett frequently referred to black people using a 'c' word that rhymes with spoon.
I can only assume that it's to do with where the audience's sympathies lie. Alf Garnett is meant to be a pompous, objectionable character with whom the audience is not meant to identify or sympathise, although Warren Mitchell's performance does often slip into pathos.
Was Jack Smethurst's character in LTN in some way meant to be more 'cuddly', someone with whom a predominately white audience could have sympathy or, worse still, empathy? Again, a genuine question. Sorry if I'm missing the obvious, but I'd love someone to explain it to me!