Oops, my bad again :'( :-[ :-[ :-[
You are from London VO and so things might work different there. Since you just received your PER, I suggest you to wait until London VO contacts you regarding your app.
NDVO might as well accept birth certificates, but as I told, the parents names might not be clear there. In India, birth certificates are usually not VERY correct and often we need to run around to get CORRECT details on them. For eg. My birth certificate just had a _____ next to the name(It took about 6 months to name me and they had to register my birth before that), half of my father's first name and my mother's name spelt wrong. It did take about a couple of months running around for me to correct ALL of the details before we submitted our application.
So, ALL I said was to be correlated to your situation and not taken as such
Hope for good news from you soon..
Thanks,
Indira Prabhakaran.