Home Office Policy Guidance, IDI, Appendix FM Section 1.0b Family Life (as a Partner or Parent) and Private Life: 10-Year Routes, August 2015, currently summarises at Paragraph 3.5:
The 10–year parent route provides a basis on which leave to remain can be granted to a parent who has responsibility for or access to their child following the breakdown of their relationship with the child’s other parent.
This route is for single parents who:
have sole parental responsibility for their child; or
are the parent with whom the child normally lives, rather than the child’s other parent (who is British or settled); or
do not live with the child (who instead lives with a British or settled parent or carer), but they have direct access in person to the child, as agreed with the parent or carer with whom the child normally lives, or as ordered by a court in the UK.
The parent route is therefore not for couples with a child together who are in a genuine and subsisting relationship. An applicant can only apply for the parent route if they are not eligible to apply for the partner route.
So what can parents with an irregular immigration status do where they have a child born in the UK who is a British citizen?
It is very possible for such parents to have a British citizen child whilst they themselves are without any leave to remain in the UK. A child can apply to register to become a British citizen if they were born in the UK on or after 1 January 1983 and neither of their parents was a British citizen or settled at that time. The child must be 10 or older and have lived in the UK until they were 10 or older. The child must also normally have spent no more than 90 days outside the UK in each of the first 10 years of their life. If the child has spent more time than this outside the UK but there are special reasons for this, there will need to be explanations provided.
Affected parents can proceed with an application to the Home Office placing reliance upon the very same policy guidance referred to above to drive home the argument that they are nonetheless still entitled to be granted leave to remain on account of the fact that they have a British citizen child in the UK.
RELIANCE UPON HOME OFFICE POLICY GUIDANCE
The above Home Office Policy Guidance provides:
“9. Exceptional Circumstances
Where an applicant does not meet the requirements of the Rules under Appendix FM and paragraph 276ADE(1)-DH, the decision maker must go on in every case to consider whether there are exceptional circumstances which warrant a grant of leave outside the Rules on Article 8 grounds.
11.2.3. Would it be unreasonable to expect a British Citizen child to leave the UK?
Save in cases involving criminality, the decision maker must not take a decision in relation to the parent or primary carer of a British Citizen child where the effect of that decision would be to force that British child to leave the EU, regardless of the age of that child. This reflects the European Court of Justice judgment in Zambrano.
Where a decision to refuse the application would require a parent or primary carer to return to a country outside the EU, the case must always be assessed on the basis that it would be unreasonable to expect a British Citizen child to leave the EU with that parent or primary carer.
Where the applicant has made an application under the family and/or private life Immigration Rules, the application must:
a) be considered under those Immigration Rules first;
b) where the applicant falls for refusal, the decision maker must go on to consider whether there are any exceptional circumstances that would warrant a grant of leave to remain outside the Immigration Rules; and
c) where the applicant falls for refusal under the Immigration Rules and there are no exceptional circumstances, and where satisfactory evidence has been provided that all of the following criteria are met, the case must be referred to European Casework for review:
i.the child is under the age of 18; and
ii.the child is a British Citizen; and
iii. the primary carer (care responsibilities and court orders are examples of evidence) of the child is a non-EEA national in the UK; and
iv.there is no other parent/guardian/carer upon whom the child is dependent or who could care for the child if the primary carer left the UK to go to a country outside the EU.
The originating decision maker should not issue a decision on the Immigration Rules application whilst awaiting this Zambrano decision.
The originating decision maker must not grant leave outside the Rules because they believe the applicant has a Zambrano right, but must instead always refer the case to European Casework for them to review and determine the case under EU law if the criteria above are met.
European Casework will decide whether or not the person has established a right to reside in the UK under EU law, and will notify the originating decision maker of that decision. European Casework will then return the case file to the originating decision maker.
The originating decision maker must then serve the Zambrano decision on the applicant, together with the decision on the original application under the Immigration Rules.
In cases where a decision to refuse the application would require a parent or primary carer to return to a country within the EU, it may be possible to require the child to return or go there with that person. However, consideration must still be given to whether it would be reasonable to expect the child to leave the UK.
SOME RELEVANT CASELAW
ZH (Tanzania) v Secretary of State for the Home Department  UKSC 4 :
Paragraphs 30, 32, 44, 46 and 47
Campbell (exclusion; Zambrano)  UKUT 00147 (IAC):
Headnote to the case
CHOICE OF APPLICATION FORUM
For such parents with British citizen children, consideration can be given to submitting applications either using form FLR (FP) or Derivative Residence Card Application, Form DRF1:
Reliance upon application FLR (FP). The current Home Office application fee per applicant is £811.00 and £500.00 is also due to the Home Office per applicant (subject to satisfying the fee waiver requirements where appropriate).Where leave to remain is granted, this will be for a period of 30 months at a time on the 10-year route to settlement. The Grant of Leave letter will normally inform the parents as follows: “You do not meet all of the Immigration Rules for a grant of leave under R-LTRP 1.1(a), (b) and (d), R-LTRPT 1.1 (a)(b) and (d) of Appendix FM. or Paragraph 276ADE(1). Please see separate refusal notice. Consideration has been given outside the Immigration Rules and due to your particular circumstances that you have a parental relationship with your British child it has been decided to grant you a period of leave outside the rules on an exceptional basis”.
Reliance upon Derivative Residence Card Application Form DRF1, as either the sole primary carer of a British citizen child or joint primary carer who shares caring responsibility for a British citizen equally with another person(‘Zambrano’). There is a fee of £65 for each person applying for a derivative residence card. Where two primary carers both claim a derivative right of residence and neither person is exempt, the application must be considered on the basis that both people would be required to leave the UK. Where a person has applied for a derivative residence card, they will be issued a Certificate of Application which confirms that a person is entitled to take employment or self-employment whilst that application remains outstanding. Derivative residence cards are generally issued for five years at a time. A person with a derivative right of residence cannot however obtain permanent residence in the UK under the EEA Regulations.