Jim posted the snippet in The Guardian by Mippy from Leeds who said
'. . . Fanny Fanakapan has always been used in my family to get the attention of somebody who had wandered off from the group when we were out as in - "Oi Fanny Fanakapan! Over here!" --Mippy, Leeds, UK'
My father, originally from Lodge Lane in Liverpool, never gave a forename but used the surname in just that way - "Oi, Fanakapan!"
Two of his other regular characters to use when he wasn't sure of someone's actual name were -
"Icky the Firebobby", who I think was originally a character referred to by Derek Guyler (a Liverpool character actor and comedian); and
"Jimmy from Pegrams" - Pegrams was a chain of butchers in Liverpool. This was often used when no-one would admit who'd done something. Who did that? Must have been Jimmy from Pegrams.
I didn't realise that 'Fanakapan' in whatever spelling came from a song by Our Gracie, but it certainly brought back pleasant memories of my father - so thanks all for that!