The demesne* in which St Birinus Catholic Church stands was given by the Davey family, a recusant** family living at Overy just across the river Thame from Dorchester village.
The land is divided into approximately three equal parts. The Presbytery and its adjoining garden on the bank of the Thame east of the church. The church is west-east aligned with, externally on the west wall a statue of St Birinus.
Embracing the church to the North, East and West is a cemetery. Under the East Window is an area for the burial of those cremated.
*Demesne: A piece of land attached to a manor and retained by the owner for their own use.
**Recusant: An English Roman Catholic of the time from about 1570 to 1791 who refused to attend services of the Church of England and thereby committed a statutory offence.