The genealogist Lukasz Bielecki in Poznan (who reads Polish, naturally) has some supportive comments for the Krakow baptism. I sent him the scan and asked particularly about Adam's later reference to his father as a barrister, and the denomination of the church. His prompt reply:
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Of course it is a Catholic church. We had really very few native Polish Protestants (if we forget people of German descent, sometimes distant). I assume when he made his life in Scotland, he just joined the mainstream church that is in Scotland. I think being Catholic in Britain was still
hard those days.
This may be the right Adam Tomasz, son of Piotr. It is hard to believe such a combination would happen often, and the social position of the father seems adequate. Barrister might not necessarily have been meant in a super-strict sense, maybe more like someone into law generally. In this
particular record, Adam is listed as customs officer. But being a customs officer assumes some degree of education, maybe in law, so it is plausible. If the family were farmers or day laborers, I would also think it was just a coincidence of names.
The issue with the letter is just anecdotal. The library arose from a collection of books and other artefacts gathered by a Poznan based count in the 19th century. Maybe he acquired the letters of a Parisian Polish emigrant just because he found them relevant, and that's why this letter is now in Poznan.
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I'm willing to accept that this is our man, and have made that case to my cousin. Piotr might have been a customs officer in 1812 but have risen to something more like a barrister by 1842, when Adam gave him that title in his second marriage documents.
Geoff