Yes, the father is named on the birth certificate. After the separation, the boy the lived with his father for some time but has been with his mother since September 2009 and I have been financially supporting both since then; the father having no financial input and little contact since that date. The father is not contesting custody but, equally, the father is unaware of my existence.
The intention was that the boy would be brought to the UK by my fiancee's mother during her break from teaching in April/May. This looks highly unlikely now due to delays in getting annulment. That is why I am thinking it best for the boy to come to the UK on a Fiancee Visa. But I think the Visa authorities may refuse unless we can show the boy would suffer hardship for perhaps the 2-3 months it would take to bring him here after my fiancee arrives.