As they were married your partner has automatic parental responsibility:
Who has parental responsibility?
If the parents of a child are married to each other or if they have jointly adopted a child, then they both have parental responsibility.
http://tinyurl.com/3fr3hv
This means he automatically has the same rights as the child's mother,unless there is something significant you haven't mentioned - had he lost contact for a long time, for example?
How old is the child?