I've always had trouble with this because it means he was about 55 when he married a young teenager Margaret Kelvie abt 1742, and had children very regularly until he wasn't far off 80 for the last one. It's possible I suppose, but very unusual.

The mother of the 10 Oct 1687 John is presumably Margery Lowny als Woods who was buried 6 Mar 1687/88, about 6 months after the baptism. Her will mentions "infant child Phillip Lowny". There was another John bapt 29 Jul 1667, likely John & Margery's first child. They might have had two Johns, though their wills only mention one. There wasn't time for her to have another child after the Oct 1687 baptism. It's not a late baptism because there's no gap. It's my opinion that "Philip" and the 1687 "John" are one and the same, and the child is supposed to be Philip. He might have died very young. It's a theory only, at this point.