They do make you jump through hoops don't they?!
I remember a woman once (work colleague some 10 years back, I will call her Jane.) She lived with her dad - a British born man, and her mother was Filipina. Her mother had never become a British citizen, and had never married Jane's dad. She never got proper visas, she was working illegally, and was staying in the UK illegally.
Jane's mother left the UK and went back to the Philippines when Jane was 5.
Jane was in her early to mid 20s when I knew her, and had only seen her mother twice since she was 5. Once when she was 10, and once when she was 12. Both times, her mother visited for a few weeks. Sadly, her mother lost touch after that, and Jane never knew where she was. Her dad got married to another woman when she was 14, and she had a half sister.
Long story short, Jane went to get a passport when she was 23, and she couldn't get one, because her mother was not a British citizen, and had never been married to her dad. AND she had never been here legally. She could not get hold of her, and could not get hold of her birth certificate. Even if she could have got it, it would not have helped as her mother was Filipina! (Oh, and she DEFINITELY never knew who her grandparents were on her mother's side. OR where they were! So she would never have got their birth certificates either.)
She left the workplace about 6 or 7 months later, and I don't know if she ever got a passport! I guess SOMETHING must have been done eventually, but yeah, her mum being a non-Brit, and not being married to her dad, caused huge problems when applying for a passport. They basically refused her.
Good luck @Pinkwithwhite !!! Sorry about that - but your issue just brought all this back to me!