one last post on this topic based on personal experience
After my wife applied & paid for her UKM & just shortly before the notification of her qualification & acceptance letter arrived - I went back again to see if she could be brit without having to go the full hock of registration
We were notified that using the NS form woud do it - simply provide the proof, or were the Brits just trying to say no one more time!
Well, we never did it, but here are the circumstances. If its too boring then dont read on.
-Born in Canada to a Brit born mother & Canadian born dad, she lived in the
UK 50's/60's timeframe for a period of over 10 years well into adulthood, without a visa, she schooled worked - no problem [important fact]
-Her Canadian born Dad [of a British born mother & Maltese born dad] also lived & worked in the UK without a visa during the 50/60's. [important fact]
-We were married before the nationality act changed [important fact]
-Her Canadian passport prior to the nationality act changed - stated she was a
British subject [semi important fact]
-Did she simply [fall through that crack in the window] get caught between doors around the time the nationality act was changing - that a 'certificate of patriality' was issued to her & very few people rather than just give her the Brit passport [important fact]
-At a point when the Canadian passport no longer indicated she was a British subject, she still entered the UK with an expired patriality certificate & without a certificate of entitlement & worked. Was that illegal at the time - may be yes, maybe no, well, we were too unconcerned to know or worry about it
There are folks that get pushed back, give up & forget - then there are others, thanks to the ease & access of information available on the world wide web who have a chance to get what is rightfully theirs
Excuse me for boring you
Disclaimer: I am not an immigration expert & anything that I post on visa & immigration is based soley on more than 30 years of personal experience & interaction with the UKBA & Home office.