If you are patient enough things turn up eventually.
Back about 4 years Linda pointed me to a post on a Black Watch web site that was about one of our HENDERSON/McGREGOR descendants. However as the post was dated 1998, it was likely that the email was inactive, and so it proved.
Today however, the poster found my WorldConnect db LornaHenderson and left a post-it against his father's entry, and sent me an email.
Contact has been made.
With the hints received so far, further digging has added a few more dates and confirmed birth places to the family of James WATT and Jane D JOHNSON of Dunfermline, then Montreal, and their immigration records have been found.