Ireland Genealogy - Gen208 - Mother Hubbard's Cupboard:
"A bishop's diocese comprised parishes. Many parishes were villages with a church and a clergyman (or incumbent.)
Larger towns and cities would contain several parishes.

Records of British baptisms, marriages and burials have been maintained by law since 1538.

Not all churches date back to 16th century and not all clergymen kept proper records in the early years.

The early baptism, marriage and burial records were usually jumbled together and some of them were written in Latin but by 1732 all registers were required to be written in English.

During 18th century the baptisms, marriages and burials were maintained inseparate registers or on separate pages.
For the first 200 years it was normal to record only the father's full name and that of his child in baptismal entries so proving ancestry for a popular surname is often difficult. Most original parish registers are today in CROs but some are still in churches.

From 1598 the clergy had to send a copy of their entire year's parish register to the local bishop. These copy entries are known as the Bishops' Transcripts or BTs.

Thanks to the efforts of LDS, microfilmed copies of most parish registers and BTs are available for loan at most FHCs. (There is a delay whilst copies are made from masters atSalt Lake City.) There are also holdings at the PRO.
Microfiche and microfilm copies are available for scrutiny at the SoG and various libraries.
Considerable work has been undertaken by FHSs in indexing the registers, and typewritten indexes and abstracts can be viewed at SoG, CROs and FHSs. "