I can see 2 baptisms in Lincolnshire for a Robert Tinker -
15/3/1751 Robt s/o Matt and Mary at Sutton Le Marsh -I have no idea of the geography but it doesn't look that far away from West Rasen
27/3/1749 at Rippingale s/o William and Susanna - this looks a long way from West Rasen
Are any of these names used by Robert for his children? That might be a clue.