The year of birth is an estimate from the year of their daughters birth.
IT sure looks like the Registrar misunderstood the Groom's last name, "Cock" instead of "Coe"............... so this needs a 2nd source...........
Marriage St. John's Parish" Register
William Cock & Susanhah Harriott were marr'd June 18th 1752 ." 
Source: S-2047177890 Repository: #R-2138127636 Title: Ancestry Family Trees Publication: Online publication - Provo, UT, USA: Ancestry.com.
Birth year: 1730; Birth state: MD
Source Information:Title Family Data Collection - Individual Records Author, Edmund West, comp. Publisher-Ancestry.com Operations Inc. Publisher Date:2000-Publisher Location:Provo, UT, USA---Repository Information Name Ancestry.com