Type 4 (Child) - Application Deferred

[CabbageMan]

I'm having trouble getting my son's student visa approved and wanted to ask for some advice from folks on the board here.

Background:

• I (applicant's father) was born in Germany in the early 80s to two British parents. My father was working for a large corporation and was transferred to Germany for work. My mother did not work in Germany. Neither ever worked for British government / military. They had no idea that being born abroad would affect my "Britishness" (British by descent only").
• I married a Philippine citizen and my son was born in the UAE in the late 00s.
• I was told by the British embassy in Dubai that my son wouldn't be eligible for British citizenship due to my being British by descent and his mother non-British. He has a Philippine passport only.
• I went to boarding school for 5 years in the UK but each year I was out of country for more than 90 days. Aside from that I have never lived or worked in the UK.
• We had a "status trace" done last year to explore all the options as to how my son may be eligible for British citizenship, but they could not find any routes.
• My son has already had a number of longer term visit visas as we travel to the UK regularly to see family, which haven't posed a problem so far.

We have applied for a Type 4 (Child) visa, but they have deferred the application on the following grounds:

Your application has been assessed by an Entry Clearance Officer (ECO) who has noted that you may qualify for Right of Abode (RoA) as your birth father is a British Citizen.

Section 1(1) of the Immigration Act 1971 confers complete exemption from UK immigration control on persons with the right of abode, subject to proof of that right. A certificate of entitlement (CoE) that is placed in a person’s passport simply provides proof of that right. However, whether the person has a COE or not they still have the right of abode in the UK. Therefore, leave cannot be granted under the Immigration Rules if you do qualify for RoA..

I responded to explain that I was born to two British parents in Germany and am therefore British by descent only. I was not able to provide my birth certificate due to loss, but my passport clearly states my birth location.

They have again deferred my application, saying:

Please provide the following documentation URGENTLY:

- Your father's Birth Certificate;
- Any other details/documents concerning how and when your father obtained his British Citizenship; and
- Details/documents concerning your father's parents' (ie. your paternal grandparents') circumstances when he was born in Germany (such as if they were serving in the British Army or posted abroad as UK civil servants).

I have requested a replacement birth certificate but it hasn't arrived yet and the German authorities to email me a scanned copy (thanks!). Hopefully it will arrive before my deadline next Friday.

I have a signed letter from my mother stating the circumstances of my birth (that neither of my parents were engaged by the government / in military service when I was born abroad).

I have the status trace and a list of my travel movements during my years in boarding school.

Do you think this will be sufficient to have the visa approved?