@Billyjoe She refused to put white British as, in her words, “I didn’t look it”.
Jaw actually dropped reading this. I think you're right to make a complaint.
I've a friend whom you'd never know is mixed. She has the "full english rose" aesthetic going on. I've been friends with her for 3 years before she confided in me that her mum is full Ghanian (black). She said she doesn't say this to alot of people because from experience, they see her differently afterwards, which is sad. I can imagine the midwife would have no problem ticking her as white because "she looks it".
My Igbo/Nigerian friend I used to work with told me once she was registering her child for something (can't quite remember) and there were two ladies sat in front of her, one was a trainee - an older white lady, the other a much younger white lady.
When the younger lady asked her nationality, she told her and a few moments later, the older white lady (trainee, who was just observing) made a comment about what the main lady (the younger one) had written down.
It happened that the younger lady was supposed to ask the ethnicity of the child but had assumed fully black because (as she said to the older one) "She clearly looks it" and the older one (surprisingly) told her there's no way she can know just by looking. The younger one in a huff then asked my friend and what do you know? Her child was mixed! My friend said she had second hand embarrassment for the younger lady and wished she could lie to protect her ego but on the other hand, she was so appreciative of the older woman's awareness and standing up to who was meant to be her trainer that she gave her a visibly thankful nod. The younger lady didn't know where to look after that.
She said the point wasn't that she assumed but she didn't feel the need to ask even when she was supposed to as it was an official form. She said the obvious nonchalant attitude the younger lady had throughout the meeting changed a bit after that blunder.