This description is provided by Olive Thexton of Fylde Branch.

Registration of births became compulsory from 1st July 1837. The compulsion was on the registrar to seek out the parents of the newly born and register the births. It is thought a number escaped his ministrations. 

Many births were not registered until it became compulsory in 1875 when the onus was put on the parents and the compulsory bit backed up by penalties. 

The introduction of compulsory vaccination is thought to have reduced the number of registrations. 

There was also in the early days a little registration of non-existent births as the registrar was paid by results! The central copies are reasonably accurate, though both they and the indexes will suffer from occasional mis-transcription. 

Some entries do not contain Christian names, because they had not been chosen by the time of registration, or differing ones from those eventually chosen. 

Some non-conformists, but not Anglican and Roman Catholic parish churches kept records of births, not baptisms. The practice almost universally ceased in 1837, and the Registrar-General received their existing records.