1) the second name. Cedric and then what is the second name?
I wonder if it might be Elwes - which appears to be a surname. However, it won't be the child's surname, as a birth registration/certificate for that date would record only the child's forenames. The surname would be inferred from the parents' details.
....it is the last name in that box
The image shows the top of some more writing which appears to be in the same box. What is that?
2) On the right, in different handwriting to the original. I think it says "Adopted" and then "? Superintendant registrar". It may be that the second word is just a signature therefore - what do you think?
Does anyone have any other insights into whether I could discover more about the adoption? My reading suggests that this would not be easy unless I am next of kin (I am not and this boy died a long time ago).
Yes, I think it says Adopted, then the superintendent registrar's signature and title. However, your query puzzles me and might suggest you already know more than we might be able to find out. Either (a) your link is pre-adoption, so how do you know the child has died? Or (b) your link is post-adoption, so how did you manage to link him to this birth registration? Or could it be (c) where a child remains part of a birth parent's family but is adopted by a step-parent?
Adoption isn't one of my strong points, but I understand that it's only adopted people or their descendants who can get access to the full records. However, I believe you might be able to get a copy of the Adoption Certificate, which would tell you the names of the adoptive parents. Someone please correct me on this if I'm wrong. Also see the GRO guide:
https://www.gro.gov.uk/gro/content/certificates/images/CG6_2.pdf