Stay with it, I'm not going off topic.
The casting director must have been have been a big Joy Division fan and fancied having a laugh. The opening 15 minutes are basically Sam Riley vs Sean Harris: Ian Curtis versus Ian Curtis. Totally freaked me out.
Then Control's Tony Wilson (Parkinson) makes an appearance. Then 24HrPP's Martin Hannett (Serkis).
I'm sure I also spotted Stephen Morris selling doughnuts on the pier too.
I'm expecting Gretton vs Gretton and Wilson vs Wilson as distinct possibilities in the future.