The Court of Appeal ruled on 3 conjoined cases in December 2017 where the key question was whether the Zambrano principle had been extended by the CJEU decision of Chavez - Vilchez. Case C-133/15 which found that a third-country national may, as the parent of a minor child who is an EU citizen, rely on a derived right of residence in the EU.
The Court ruled that there was no such extension and whilst the consideration of respect for family life was a relevant factor, it did not lead to a conclusion that residency rights were a given. The matter remains one of compulsion.
In the case of Patel, Shah & Bourouisa EWCA Civ 2028  , they highlighted that the Zambrano principle cannot be regarded as a back door route to residency by non EU citizen parents who otherwise do not meet the requirements of the Immigration rules [74 - 76]
The correct approach, in a case involving a British citizen child, is to ask whether the situation of the child is such that, if the non-EU citizen parent left the EU, the British citizen would be unable to care for the child, so that the child would be compelled to leave (para 77). While consideration of respect for family life was a relevant factor, it could not result in an automatic conclusion that residency should be permitted as a result of the child being compelled to leave because family life would be diminished by the departure of one parent (para 78) :
I would wish to emphasise that consideration of the respect for family life (whether considered under Article 8 ECHR or Article 7 of the Charter), although a relevant factor, cannot be a trump card enabling a court or tribunal to conclude that a child will be compelled to leave because Article 8 (or Article 7) are engaged and family life will be diminished by the departure of one parent. Family life will be diminished by the departure of one parent in the great majority of cases. The question remains whether, all things considered, the departure of the parent will mean the child is compelled to follow.
It concluded that where the British parent was capable of looking after the child, there was no proper basis for a finding of compulsion (para 79).