Hi Lizdee
I could not find Williams baptism but l did find the following which may prove useful?
Suffolk Sudbury marriage licences 1755-1781
Book 15 1765-1766
County Suffolk
Wm.Sparkes, of Mildenhall,gent, s.m, 23 years & Frances Rickwood, of same, s.w, at same.Bn:Phillip Rickwood,Gent [no date]
Suffolk Sudbury marriage licences 1755-1781
Book 15 1765-1766
County Suffolk
Saml Satchell, of Isleham, s.m, tailor, & Margaretta Sparkes, s.w of Mildenhall, at same.
Bn: brother,Wm. Sparkes 25 Feb 1765
Good luck and l hope the above is useful
Robert