As well as the other ones listed above, all of which are great, could I possibly recommend a little known movie called Hard Men? To be perfectly honest it's one of those you'll either love or hate (I loved it), and even if you're not a fan of London/British gangster films it's still worth a look.

As far as I know it's readily available on video/DVD. A synopsis of the film can be found at the IMdB page here