2 points that i think are of importance here,
1, Was Bernard Manning a great Comedian, This has to be answered with out a doubt Yes, BM was technically a comic genius, his ability to deliver a punchline was incredible.
2, Was his material out dated and offensive in this modern world.... again Yes,

My perception of him is that its a shame he wasnt born 40 years later, i think he would have been one of the greatest comedians of all time, he was a victim of his generation. You cant really hold that against him, At the end of the day, he only ever told a few jokes, made some people laugh, made other people take a look at the society they lived in and made some other people rant on discussion forums,,,, over all, he wasnt a bad man, so i say R.I.P Bernard Manning, a great comedian, born too early..