Post
by Richard W » Fri Feb 12, 2016 5:20 am
The key question is whether your father was British 'other than [merely] by descent'.
When your father was born, was your grandfather in Mexico on 'Crown Service' or working for an inter-governmental organisation or similar? This could make your father British other than by descent, and then you are probably already British.
If your father was only British by descent, there are limited circumstances in which you may be registered as British if you are under 18. So, are you under 18? How long was your father in the UK before you were born? Are you in the UK now? What about British overseas territories?
Did your father ever renounce British citizenship?