The Barney Mysteries were a series of six children's books written by British author Enid Blyton.
Their irritating, mischievous younger cousin Snubby (whose real name is Peter) comes to stay with them during the school holidays, as he has no parents.
During their first adventure, they meet Barney (his actual name is Barnabas), who makes an appearance in each of the succeeding books.
Snoek was shipped in tins to the UK during WW2 but it was not popular and was mainly fed to pet cats.
After the war, the fish was not imported and younger readers wouldn't know what it was, and so the pet cat was renamed.