The Telegraph report says that: "The ruling means that the child now effectively has two fathers and that the person who raised him, referred to only as Mr A, has the same rights as the boy's biological parent." I'm not sure about this, as the report doesn't explain whether the natural father has parental responsibility - if he does not, then he does not have the same rights.
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Update: The full report of this case, Re A (A Child: Joint Residence/Parental Responsibility)  EWCA Civ 867 can now be found here. The report confirms that the boy's natural father "wished to play no significant part in [his] life". I think that what may have confused the Telegraph reporter into thinking that there was no limit to the number of parents that a child can have was Sir Mark Potter's confirmation that under the Children Act there is no limit upon the number of persons who may have parental responsibility for the same child at the same time.