The earliest reference to a church in Hillingdon is the grant by Brian Fitz Count, Lord of Colham Manor, of Hillingdon Church to Evesham Abbey, Worcestershire shortly after 1100. Nothing remains of that building. The present church is built mainly of flint rubble with stone dressings. The oldest part of the building is the re-set chancel arch which has ""stiff-leaf"" foliage capitals of the thirteenth century. The church was thoroughly restored by George Gilbert Scott in 1847/8 when the nave was lengthened, the transepts were added and the present east end, including the chancel with flanking chapels, was built. The building was restored in 1902 and again in 1953-5, and a new north-east vestry was added in 1964. By 1819 the churchyard had become full and it was enlarged by incorporating part of Coney Green on the south side. It again became full and in 1867 it was closed to burials in new graves, although burials continued of family members in existing graves. The last such burial was in 1948.
When using the earliest registers it may be helpful to be aware of certain aspects of the law relating to parish record keeping during the period of the Civil War and the Commonwealth 1642-1660. On 6 December 1644 (taking effect 4 January 1645) an ordinance required that each parish should record the dates of baptisms, plus the dates of birth and the parents names. Each burial entry was to record also the date of death. Few parishes observed these directions. An Act of Parliament of 24 August 1653 (taking effect 29 September 1653) which legalised civil marriage took away from ministers custody of the registers and the solemnisation of the marriage ceremony. This latter duty was passed to the Justices. The registers were to be kept by a new secular official, the 'Parish Register', elected by all the rate payers in a parish, and sworn before, and approved by, a magistrate. At St John, Hillingdon, the appointment of the Register (Robert Newington, the parish clerk) is recorded in DRO/110/002 on 19 September 1653. All registration functions were entrusted to these officials. A common feature of parish registers at this time (and which occurs in those of St John, Hillingdon) is the entry of dates of birth and publication of marriage, as well as, or instead of, those of baptism and marriage. The marriage ordinance was confirmed in 1657 but the declaration that marriages, other than those conducted by the Justices, were illegal was omitted. In many places, from then until the end of the Commonwealth, marriages were celebrated by magistrate and Register jointly. The effects of this upheaval can be seen in the haphazard nature of the entries from this period in DRO/110/001. Later entries are usually duplicated in DRO/110/002, sometimes with slightly altered spellings.