你看看这段吧——
Before 1 July 2006, those born to British fathers could only claim British citizenship if their parents were married.
If a child was born to unmarried parents, an application to register a child under 18 would have been possible but these were considered at the discretion of the Home Secretary and citizenship could not be guaranteed.
Now, thanks to the recent enactment of the Immigration Act 2014, those who were previously disadvantaged by the earlier law can obtain citizenship through their UK-born father, irrespective of whether their parents were married.
Proof of eligibility
To qualify for citizenship under the new conditions, amongst other things, the applicant will need to be able to prove that they would have been eligible for UK citizenship if their parents had been married at the time of their birth. Evidence of paternity will be required.