see here www.rbkc.gov.uk/pdf/FPI%20is%20it%20legal%20Feb_08.pdf
The law sets out who has parental responsibility. You have it automatically if you are:
l The biological mother of the child
l The biological father of the child, and were married to the mother at the
time of conception or birth, or you married the mother after the birth of the child or, for babies born since 2003, you registered the birth of the baby with the mother
l You are adoptive parents once an adoption order is made.
Even if the marriage breaks down, both father and mother will continue to have parental responsibility. Unmarried fathers did not have the same rights and responsibilities as a married father. The Adoption and Children Act 2002 now gives an unmarried father parental responsibility where he and the mother register the birth of their child together.
Even if the unmarried father’s name is not on the original birth certificate, you can now re-register the birth at a later date, adding the father’s details. This will give the father parental responsibility.
See www.gro.gov.uk.
But the Act is not retrospective, so unmarried fathers with children born before 1 December 2003 can still only get a parental responsibility agreement, either by:
l Making an agreement with the mother
l Or by applying to the court for a parental responsibility order.
Unmarried couples wishing to obtain a parental responsibility
agreement have to:
l Obtain a form from a solicitor or family court
l Go in person to the local magistrates court or County Court to get it signed
l Send it to the Principal Registry of the Family Division.
You should note also that an unmarried father who has not got parental
responsibility will have to apply for a court order to obtain the right, if the mother dies.