A young girl whose parents cannot care for her should be brought up by a stranger rather than her grandparents, a family court hearing in Croydon has concluded.

District Judge Graham Keating has placed the youngster with a woman she has never met, instead of her father's parents, under a "special guardianship" order.

He said a "holistic analysis" of evidence points to the woman, a friend of the girl's mother, being the best option.

He said the strength of the blood relationship is "very powerful" but "not definitive".

The judge outlined his decision in a written ruling published following a private family court hearing in Croydon, south London.

He said the girl, who was born in 2017 and whose parents had separated, could not be identified in media reports.

Social services bosses at Croydon Council have responsibility for the girl's welfare and had asked for a ruling about where she should live.

They were in favour of the girl moving to live with her mother's friend.

Judge Keating indicated that the girl had already temporarily been removed from home pending decisions on her long-term future.

He ruled out the girl's father, a foreigner serving a prison sentence after being convicted of assaulting the girl's mother and facing deportation on release, as a carer.

He said there were three possible realistic care options: the mother, the father's parents, who lived in Europe, or the mother's friend.

The judge said the mother had many "challenging" problems, including a drink problem, and was unable to "adequately" care for her daughter.

He said he had significant doubts about the girl's father's parents' ability to meet her emotional needs - especially if she turned into a rebellious teenager.

The judge also said the girl could lose her relationship with her mother if she moved to live with her father's parents.

But he said the mother's friend offered a "unique possibility".

He said the woman had successfully raised a daughter through "those troubled teenage years", would allow the girl to maintain a meaningful relationship with her mother and was willing to promote her relationship with her father's family.

"How can it be right that if a child cannot be cared for by her parents, she is placed with a stranger in preference to her grandparents?" Judge Keating asked in his ruling.

"The answer comes from a recognition that the strength of the blood relationship is very powerful; however, it is not definitive."

He added: "I have based my conclusion on an holistic analysis for the benefits of all of the realistic options.

"(The mother) offers unconditional love and a powerful relationship but cannot be regarded as sufficiently safe.

"(Her friend) is able to meet (the girl's) needs but has no blood relationship with (the girl).

"She does, though, allow the means for the existing relationships with the mother and maternal family and the development of the relationships with (the girl's) paternal family.

"(The father's parents) offer unconditional love, a paternal family upbringing; however that likely loss of, or at least significantly reduced, relationship with her mother.

"That, to my mind, is the magnetic fact to which I am drawn.

"I have reached the clear view that (the girl's) needs are best met by a special guardianship order in favour of (the mother's friend)."