Rosalie,
Managed to spend some time at the CCRO this morning. Firstly, your query about William SWAN/SWANN who died aged 97 in 1831...
Found his two marriages: In Dullingham 11-04-1769, William bac. of Brinkley to Elizabeth RAMPSHIRE (signs RAMSHER); this followed by a baptism of a William SWANN, s. of William SWANN on 20-04-1769 (I may have got the year of his first marriage wrong - might have been 1767...).
Then the second marriage at Burrough Green: William SWANN o.t.p. widower to Unity SHEARMAN o.t.p.
So, armed with the Brinkley indication, I began to search for his baptism circa 1734: first SWANN baptism in Brinkley not until 1822; earliest SWANN baptism in Burrough Green 1771; earliest SWANN baptism in Dullingham was 1769.
Had a look at the parish map for the 18thC then, and tried some of the other nearby parishes, namely Westley Waterless, Stetchworth, Weston Colville, Carlton cum Willingham, even Bottisham, the Swaffhams and the Wilbrahams...
No sign of him, sad to say, the only baptism for a SWAN I came up with was in Bottisham: 03-08-1732: Robert s. of Valentine and Dorothy SWAN; and 15-09-1734 Mary d. of same parents.
Where are you William...? Be back presently to tell you about those 2 marriages you were after.
Keith