Update 2025
I have now found, with more experience, that I should have investigated the family more before posting the above question as it is not actually valid.
I have now found that William was buried in 1788, so cannot be Charlotte’s father, and Elizabeth probably remarried in 1798 to James Witbey. There was also a further child in 1788, Charles William, and an illegitimate child in 1796 for Elizabeth, Elizabeth Cave Issit.
Ann was buried in 1786 but the other three all went on to marry and the only son stayed in Leicestershire. So no Issits from this family came to Oxfordshire!