Everyone else has a surname, why not Sam?
We know he's uncle to the Jones twins, but not whether he's brother to Charlie or Bronwen (assuming they're married and she took Charlie's name of course).
Perhaps he's Sam Samuels, like Tom Thomas.
Or maybe Sam is his surname. In which case I need to know his first name.
Perhap's he's Station Officer Steele's son, and so everyone calls him Sam to avoid unnecessary confusion.
Come to that, what's Trevor's surname?
DS2 has been up since 4:55 and we've been watching his new Fireman Sam DVD on loop. Can you tell?