Hi Troods,
I don't know of any ship's lists from West to East, but what about
a) immigration records. Don't know where to look, Kew is the most likely place.
b) did he "stay american" or did he become a "naturalised british subject" ?
If so, there should be records here, probaly also also at Kew. I don't know what info. is in the records, but I think I recall someone here saying that she found the naturalisation records for an ancestor and there was a lot of useful info. there.
c) Registration of Aliens - there may be records of this
See also these tips from "JDG":
http://www.rootschat.com/forum/index.php?topic=12874.msg44371#msg44371ps. Kew = National Archives:
http://www.nationalarchives.gov.uk/registration/ Check here first which records are available
Hope this helps
Good luck !
Bob