Apply for registration of a child under 18 as a British citizen

[rza22]

Hi Guys,
My two years old son does not have any passport/national identification card/travel document due to he was born in the UK. We didn't apply his Dependent Pass/ILR because we wanted to register him as a British citizen once we get our ILR. He has never been to abroad. I (father) have got my ILR and would like to apply for his British citizen, when filling out the online application form, I have reached to the following point:

"Reason for not providing identification documents
Explain why you are unable to provide a valid form of identification.
Proof of identity is usually required to make a valid application. You cannot use a national identity card to prove your identity for this application. ([ ]Maximum of 500 characters) "

Can anyone please let me know what reason will be accepted? (a sample paragraph would be appreciated)
Many thanks in advance...

[AmazonianX]

Hi Guys,
My two years old son does not have any passport/national identification card/travel document due to he was born in the UK. We didn't apply his Dependent Pass/ILR because we wanted to register him as a British citizen once we get our ILR. He has never been to abroad. I (father) have got my ILR and would like to apply for his British citizen, when filling out the online application form, I have reached to the following point:

"Reason for not providing identification documents
Explain why you are unable to provide a valid form of identification.
Proof of identity is usually required to make a valid application. You cannot use a national identity card to prove your identity for this application. ([ ]Maximum of 500 characters) "

Can anyone please let me know what reason will be accepted? (a sample paragraph would be appreciated)
Many thanks in advance...

A simple statement of how you planned to register him after you parent getting ILR will suffice.