when I had my daughter christened, the vicar went mental at me because on of the godparents was not christened and the other was not of the same faith. I nearly wet meself with fear after the dressing down he gave me.................................but he christened her all the same with these demon godparents!!
Depends what faith and vicar/church also sometimes.
My son was baptised catholic and at least one godparent had to be practicing catholic. We had to have two long meetings with vicar beforehand. Dont think CofE is quite as strict!
Having read your other post 4get, I think if your not comfortable doing it, say know, it doesnt mean you wont be there for the child.
As my sister is a Lay Reader in the Church of England i would
say Yes to God Parents to be Christened. My sister is busy with the prayers for the service on Sunday.