Your response sent me in search of the answer.
John M. Reiner. He spoke at the Tabernacle in SLC in 1898.
See the following post and the ensuing discussion for more information:
http://bycommonconsent.com/2008/01/16/a-footnote-to-the-strength-of-the-mormon-position/
As reported by an autobiography written in 1930? Hmm. Well, I guess that's something, but I suppose I still consider it to be hearsay.
Still, I can see why a Roman Catholic apologist might take the position claimed; I just don't see any unique theological reason why a Roman Catholic would think that the Mormon position was particularly strong, as compared to any other of the (many) 19th Century "Restorationist" sects (i.e., why not the Campbellite "Disciples of Christ"/"Churches of Christ" Restorationist sects?), any of which deny the validity of a "continuing" Church as acknowledged by the Protestant Reformers (who saw their work as intended to "Reform" the Church, not to "Restore" a Church that had -- allegedly -- disappeared from the Earth).
And I suppose that takes me back to your immediately prior post (#43), to which I should probably now give some more thoughtful consideration. Thanks for the answers, and the questions!!