The film was well into development when the producers learned of the existence of Legend (2015), a rival production starring Tom Hardy as both Ron and Reggie Kray.
One of three films about the Krays being released in 2015.
The barmaid Madge at The Lion where the Krays stake their territory is played by Anita Dobson. She sprang to fame playing the landlady at the Queen Vic in EastEnders (1985), a role she played for three years.
This - and its sequel - were shot on a budget of $2.5 million.