When I was young there were several in the congregations. Our P/O (then called Congregation Servant ) was an elderly dapper little man who cycled everywhere . He was serious about his faith and a serious man who would give us kids a stern look if we made a noise. But he was also kindly and hard working. He had a really deep knowledge of the Bible and it just oozed out of him . I used to think it was the Holy Spirit but now I guess it was the product of a lifetime of reading and study.
My elder sister was able to know him better than me and he once told her that the "calling" was an unmistakable feeling that he could not put into words , He "Just knew" . He certainly had a deep love and respect for "The Lord" as he used to refer to Jesus.
I think that the older ones who were there in the pre 1935 days were sincere, after all, they were the rank and file of their day. The later ones must think that they are a cut above the rest so as to claim such a thing