Your original post back in 2011 doesn't appear to have had a positive response.
Although living in Mudford, the 1851 census shows Elizabeth Flag born Queen Camel and so, this is her baptism:
Elizabeth Flagg bp.25/7/1800 Queen Camel, Somerset, dau. of Robert and Susannah.
James Flagg ditto
(sisters Mary bp.1792 and and Hannah 1796)
Susannah Flagg was buried 25/7/1800 Queen Camel (same day as Elizabeth and James baptised)
Robert bc.1764 bur.31/3/1848 Queen Camel
Robert Flagg married Susanna Willis 5/12/1791 Queen Camel
Robert Flagg bp.11/3/1764 Queen Camel, son of Robert and Mary.
James Flagg bp.29/7/1770 ditto
Robert Flagg married Mary Hodges 8/11/1757 South Cadbury, Somerset - dau. Elizabeth baptised there 3/6/1758 then a son John bp.25/12/1761 South Barrow and by 1764 family in Queen Camel.
Cannot see a likely baptism for a Robert Flagg ca.1730+/-5 in Somerset.
Annette