Pinky Brown and the Blue Angel

I have never seen the film Brighton Rock, and I've never read the book – although the latter is something I must get round to doing one of these days.

I am familiar with Pinky Brown however; he makes regular appearances in quizzes. He was played in the original (1948) film version by Richard Attenborough, and in the 2010 remake by Sam Riley (otherwise known for playing Ian Curtis in the 2007 biopic Control.)

But ... I have never heard of any Blue Angel in either the book or film, and appropriate Google searches have failed to come up with any. I am at a loss to explain where this has come from.