PROOF OF HOW BRITISH CITIZENSHIP WAS ACQUIRED

[LINDYLOU]

Wondering if anyone can help
My Husband was born in the UK in 1962 to a British mother and Italian Father,
He has a British birth certificate and a British passport
He is in the process of applying for Italian Citizenship through his father
The application has been submitted at The Italian Embassy in Athens as this is where he is now resident
The Italian Embassy in Athens have asked for a declaration from the British authorities as to how he Acquired his British citizenship, " by birth" or "through his mother" or "both"
Any ideas where I could obtain this declaration from? The British embassy here in Athens say they don't provide such a declaration, the only think I can find is at HMPO you can apply for a declaration of British Nationality status, but this seems to be for people who don't hold British Passports, and I am not sure it will state how the Citizenship was acquired, i.e. The nationality laws at the time of his birth.