As a one-time 'ARCHIEPISCOPAL PECULIAR' directly under the jurisdiction of the archbishop of Canterbury and not the local bishop (991-1838), Hadleigh has been at the forefront of church reform.
- In the 1550's Reverand Dr Rowland Taylor and his curate Richard Yeomans were martyred for their beliefs.
- In 1604-1611 John Overall and John Bois who both attended school in Hadleigh, later became translators of the King James Authorized Version of the Bible.
- In 1833 the Hadleigh Conference gave birth to the Oxford Movement.