Parish records for Holy Trinity (1866 onwards) are, by and large, available on the various family history website if you subscribe. These are Ancestry, FindmyPast, The Genealogist, MyHeritage and FamilySearch. Older records Parish records, including baptisms, marriages, banns and burials, have been made available to FamilySearch by West Sussex Record Office.
Should you have any specific enquiries not addressed by the above website, or if you are needing help with a family history research project, get in touch with Oliver Hartley, who lives in Duncton, at [email protected]