The Augustine Priory of the Holy Trinity was founded at Michelham in 1229. The Priory was dissolved in the 1537 dissolution of the monasteries by Henry VIII. The Church and some of the building were demolished and between 1599 and 1601. The house was sold to Thomas Sackville, 1st Earl of Dorset. It was then sold to James Gwynne in 1896 and was where his children Rupert, Roland and Violet grew up. The property remained in private hands into the 20th century, when it was restored by the Sussex architect and antiquarian, Walter Godfrey. It was used as a base for Canadian troops during the winter of 1941-42 while they prepared for the Dieppe Raid. Later it was the East Sussex headquarters of the Auxiliary Territorial Service.
In 1958 Mrs R.H. Hotblack purchased the property with the aim of preserving it for posterity. With an endowment from Kenneth, Earl of Inchcape, as a memorial to his friend John Fletcher Boughey who was killed during the Second World War, Mrs Hotblack gave the property in trust to the Sussex Archaeological Society on 1 November 1959.
- Pamela Cullen, "Stranger in Blood: The case files on Doctor John Bodkin Adams", 2006
- Michelham Priory Guide Book, Sussex Archaeological Society, 1995
- Michelham Priory - official site at Sussex Archaeological Society