Thanks for that

Going with born c 1777 have you considered this one?
Wm PARKER Baptised 3 March 1777, St John the Baptist, Morton by Bourne
Parents JOHN/JOYCE
Sibling;
JNO Parker Baptised 14 June 1778, St Mary, Pinchbeck to JNO/JOYCE
(FreeREG)
F/S has a Marriage 8 July 1776 Morton (Near Bourne) John PARKER/Joice MIDDLETON
FreeREG has her as JANE Middleton
So transcription errors do occur