Thank you, johnjensen, for the directory references, which I shall squirrel away.
I believe Alexander and Sarah mentioned in 1820 are children of Alexander Clindenin, schoolmaster in Killyleagh, and his wife Janet Wilson, if the information in 'The House of Glendonwyn' is correct, though sadly no sources are given in this book for the information. Samuel Alexander is their nephew, subject of this thread.
1801 presents something of a puzzle. Alexander would appear to be the same Alexander as in 1820(and yes, I believe Samuel A would have been apprenticed to his uncle). I wonder if 'Jane' is actually 'Janet', widow of Alexander the schoolmaster of Killyleagh, as she is supposed (House of Glendonwyn again) to have died in Dublin. (Alexander died intestate in 1787 in Carrick-on Suir.) The next puzzle is the listing of William, who is supposed to have died in 1797. I know directories have to be prepared in advance, but could it be four years behind the times?
As you say, all the hits for Samuel Alexander CLINDENIN on findmypast.ie are directories, except one which is from the 'Select Committee on Fictitious Votes 1837-38.' What sort of information is this likely to contain? (All my other research is in Scotland and Yorkshire, so many aspects of irish genealogy are new to me)
Regards,
Lesley