I am sure that Essie's post is correct. Essie has noted the details in the index including the maiden name of the mum. So, the surname of the child whose birth is registered is INDEXED under the mum's surname at the time of that registration.
So, the index is under KRAUSE as that is mum's surname at that time, because she is a married woman, and therefore the details for the child's father can be recorded on the birth registration.
So, the index has Albert's surname as KRAUSE and the child's father as Jno (as in Jno. KRAUSE) and the index includes mum's nee name as Eliza Jane BARTRAM.
Essie's post does not suggest that Albert's or Leslie's parents were John and Eliza BARTRAM. It suggests to me that the parents were Mr and Mrs John KRAUSE.
When you obtain the actual image of the birth registration you will notice that the registration itself does NOT include a surname for the baby.
Cheers, JM