"Yes, but also one of the problems for a novelist in Ireland is the fact that there are no formal manners. I mean some people have beautiful manners but there's no kind of agreed form of manners"

John McGahern is suggesting that the lack of official good manners in Ireland can be a problem for authors. He is suggesting that while some individuals may have good manners, there is no agreed upon form of good manners that everyone follows. This lack of official manners can be a challenge for novelists since it can be tough to properly represent the behavior of characters in a novel without a set of concurred upon good manners. This can be especially difficult for authors who are attempting to properly portray the culture of Ireland in their work. Without a set of formal manners, it can be hard to precisely represent the habits of characters in a novel.