Change of Surname
Prior to the implementation of the Children Act 1989 on 14th October 1991, under section 41 of the Matrimonial Causes Act 1973 it was routinely stated on the 'certificate of satisfaction for the arrangements for the children' that no one should take any action without the authority of the court which would result in the children being known by another name. For anyone divorced before this date their children are automatically protected and anyone taking action against this prohibition would be in contempt of court.
The child's surname is also legally protected where a Residence Order is in force. Section 13(1)(a) of the Children Act 1989 states that:
"Where a residence order is in force with respect to a child, no person may cause the child to be known by a new surname without the written consent of every person who has parental responsibility for the child or the leave of the court".
If the child's surname is not protected by a residence order or by a 'certificate of satisfaction' then an application for a Prohibited Steps Order may be necessary.
What's the situation with unmarried fathers?
Where no residence order is in force an unmarried father may apply for a Specific Issue Order to specify by which surname a child should be known. Fathers with Parental Responsibility have a right to be consulted over any change of name by deed poll (cf. Practice Direction Child: Change of Surname  1 FLR 458).
What case law exists on changes of surname?
Case law on changes of surname for children changes frequently. Leading cases include:
Dawson v Wearmouth (The Times, 26 March 1999)
In re W (a Child) etc (The Times, 5 August 1999)
What rights do unmarried fathers have over birth certificates?
The Registration of Births and Deaths Act 1953 governs the registration of names. Where the father and the mother were not married it is the duty of the mother to register the birth within 42 days.
Section 9(3)(b) states that: "The surname to be entered shall be the surname by which at the date of registration of the birth it is intended that the child shall be known".
Child's Father Registered:
Section 10(1) prohibits the Registrar from entering the father's name on the birth certificate without the co-operation and consent of the mother unless there is a court order in force. Section 10(a) allows re-registration to show the father on the certificate, but only with the consent and co-operation of the mother.