-19(c) Where the occupier becomes aware of the libel but the circumstances show that removal or obliteration is very difficult or very expensive, the fact that the defamatory statement is not expunged may well not justify the inference that it remains in place with his approval. 45. The respondents seek to argue that their situation is analogous to that of the golf club proprietors and that application of the notice board approach exonerates them from liability. F. 46. The differences between the two sets of principles It is important to appreciate the differences between the principles which derive from the notice board line of cases and those which constitute the innocent dissemination defence. 47. As analysed above, the innocent dissemination defence is a common law doctrine developed to mitigate the harshness of the strict publication rule. While it does not avail the first or main publishers it brings relief to subordinate publishers who have knowingly participated in the process of disseminating the article concerned. The defence is therefore applicable to persons who are admittedly publishers, although playing a subordinate role, allowing them to be exonerated from liability if they discharge the burden of showing that they did not know that the article which they had helped to disseminate contained the offending content and that such lack of knowledge was not due to any lack of reasonable care on their part. 48. In contrast, the occupiers in the notice board and graffiti cases have not in any sense assisted or participated in the originator’s publication of the libel. These are not cases involving anyone who has played a role in a scheme for distributing the offending publication seeking relief from the strict rule. As Greene LJ pointed out in Byrne v Deane, the posting of the defamatory verse on