Big fan of the Richard Stark Parker novels and I think Lee Marvin was about perfect for the character in this. Its been a few years since I've seen it and I thought from these photos it must've been during the flashbacks of the robbery scenes as I know they are brief - But I found that on the TCM Movies website here. And he isn't wearing it there. Then I found this on youtube and it looks like it was just worn during rehearsals/set ups. Now I look you can actually see the jacket worn in the film scenes under this one in the first photo.