Not only were are.
Parish registers record the baptisms, marriages and burials in a particular parish. They are kept in the church until full.
When the register is full the vicar (incumbent) has the option of sending the full register to the Diocesan Archive, often a county archive but not necessarily for the county the parish is in.
The vicar (incumbent) also has the option of keeping the register at the church if he/she so wishes.
In addition the second, or duplicate, marriage register is sent to the Superintendent Registrar in the same way as full civil registers.
There are good and bad points about both sides of this argument.
Having a central location allows easier searching of records and should provide better storage and security.
On the other hand if a disaster happens (fire flood etc.) there is more chance of loosing more records than if they were stored remotely.
Cheers
Guy