' John - son of a stranger born of Thos. Marshall' - 1 July 1759 - (which was a Sunday) same christening date as the London Foundling records and signed by William HAWKINS - curate.

and as you say, William HAWKINS is the Curate at the weddings in 1760 - Westbury on Severn.

???? - using the Advanced Search of children - baptised, father Thomas MARSHALL (Westbury on Severn)

Thomas MARSHALL and wife Elizabeth have children baptised at Westbury on Severn around that time.

Mary - 25 July 1754
Elizabeth 1 July 1756
Joan - 17 May 1767 (FOD records married Richard TRIGG at Westbury on Severn 18 October 1786)
Joseph - 22 July 1770
Phoebe - 27 July 1770

FOD records - burial at Westbury on Severn 8 March 1780 - Thomas MARSHALL