Hi Len,
After I posted the above message, I searched the IGI and came to the same conclusion as yourself that the Leece Clucas connection was through the son Leece (bp 1805) of Wm Clucas & Margaret Leece who married in Patrick 6 October 1781

Challenge now is to sort out which Margaret Leece . The most obvious one would be the one in the IGI bn abt 1761 d/o John Leece & Ann Parr as the only other candidate, Margaret bp 1758, German, d/o John Leece & Ellinor Clague, died in 1765.

Elizabeth