Well, I've just checked the Complete Works Of Charles Fort (NY, 1941) and there is no mention in the Index of "Neston" or "Robert Clancy" and...nothing. All references (Jan.-Dec.) for 1857...nothing.
Scott T. Felton noted (http://ufos.about.com/b/2008/04/28/witness-of-wales-ufo-crash.htm) regarding Tom Slemen on the 'UFO' crash at Berwyn Mts that:
"Tom Slemen a so called Paranormal expert writes for several local papers on ghosts, spirits, after-life and UFOs. He is not an expert. He is a compulsive liar. He creates or enhances stories to improve his readership.
"The story run by the Denbighshire Free Press in North Wales was a front page headline and almost word for word, was taken from Tom Slemen’s webpage. As a result, the nurse Mrs Pat Evans threatened to sue the paper.
"Nothing as described by Slemen is true. And it is idiots like him who have forced Mrs evans to live abroad, though her two daughters Diane and Tina still live locally in this part of North Wales."
I have tried to contact Mr. Slemen but no responses. This 1857 report just plain does not exist. It's a fabrication. Yet Ufologists still quote it as fact -again having never ever checked the alleged source or else they would have found this to be a hox (Slemen doesn't even quote which Fort book or page number!).
please, Ufologists CHECK EVERYTHING before citing it as fact "because someone said so"!