There was a George Morgan in Levuka in 1875, merchant. He is likely to have come to Fiji from Australia or NZ, rather than direct from Britain.
To find Alfred's birth registration, go to www.familysearch.org
at a Mormon Family History Centre, or an affiliated library;
search in the catalog under
Fiji > Civil registration > general birth records > Index of births 1875-1960.
He should be listed in this index, and it will give his parent's names and a reference to the actual entry, which will be on another microfilm, probably
Granite Mountain Record Vault
This can only be seen at FHCs or affiliated libraries