If you spot more than one baptism for the same person, perhaps many years apart and usually in different churches, that is a sign of nonconformity. This can be challenging if birth information is not given each time. Beware also of naming patterns so generations are not mixed up. Look for proof of the birth of each child, or evidence of the death of the first one.
For a short period in the late 1600s, Church of England clergy were required to keep a record of all persons born in the parish. Some registers show all dissenters listed at the back of a register. In some registers a child may be shown without a forename as clergy considered a child did not receive a name until baptism, usually as an infant. Many clergy also made a clear note in the register that the child being recorded was from a dissenting family. Quakers and Baptists in particular did not believe in infant baptism.
Baptism later in life, usually after the age of seven, is known as an adult baptism and this can suggest that the parents were not Church of England. Ages or birth dates may or may not be shown in the register. The existence of an adult Anglican baptism just before a marriage could also suggest that an ancestor was not Church of England at birth. Usually where an adult baptism occurs, either the age or at least the notation “adult” is recorded in a baptism register. In a few cases baptism could be in middle or old age if the person needed parish assistance. In some periods of history, people were unable to marry in the Church of England unless they were baptised members.
Sometimes baptisms of the sick or elderly may have been required if they had been nonconformists so as to qualify for parish relief.
When a committed nonconformist parent died, a surviving spouse may have had the children baptised in the Church of England because they were not fully nonconformist in their beliefs. This is a good clue as to which side of the family followed nonconformity.
If families had group baptisms, which may have included adults, this can indicate a previous period of nonconformity. Sometimes, even if children were christened as infants, if they became members of a nonconformist denomination they had to be rebaptised if they reverted to the Church of England.