BC application. How to prove residency when passport expired

[Qiman]

Dear all
My son is 18 , and is going to apply for British Citizenship. His passport expired on 15th June this year, and we forgot to renew it. It is my fault. His school finished in June this year, and he has stayed at home since. He is going to study in a university in London in Oct. He attended his GP and orthodontist during the summer. My question is how to prove his Residency from 15th June. Can I ask GP to write a letter? Thank you.

[zeusmagnanimous]

There is no issue here at all. Just renew his passport now. If the passport shows he did not leave the country after entering the last time then basically you are covered.

[Qiman]

Thanks for replying. I am Chinese, and Chinese government does not recognise dual citizenship. In order to renew the Chinese visa, my son has to get home office to certify he has not got british citizenship which is costing and time consuming.

[ban.s]

when are you planning to apply? has he got any other absences in the 12 months preceeding the application prior to his passport expiry?
Try to get letters from GP and orthodontist confirming those appointments.