It's awful, what was Karl Urban thinking with that mish mash of cartoonish nonsense? Very irritating. It's like someone on a talk show is doing a humorously bad imitation of a cockney (or similar) accent.
Also he says to Hughie "Sorry I hit you, I lost me bottle". Losing your bottle means to chicken out, not lose your temper.
And is Billy's father supposed to be British? He has an Australian accent.
He is a New Zealander, so I think that is New Zealand accent, though I wouldn't say there is that much different between Australian and New Zealand accents.
shareIf you meant the father, the actor is Australian.
If you meant Karl Urban, the accent he's butchering is nothing like Australian or Kiwi, he's doing some awful imitation of a working class British accent, I think it's supposed to be Cockney.
As for Australian and NZ accents there is a distinct difference - but yes, not very apparent to people outside of those countries.