Ok, here we go ...
Duplicate the Background layer. Immediately desaturate it by pressing Ctrl Shift U. Change its blend mode to Soft Light. This is "Layer 1" in my screenshot.
Duplicate Layer 1 to make "Layer 1 copy", and run Filter>Other>High Pass. I used a radius of about 4 because I was working on the web sized version. On the full size, you'd use somewhere between 8 and 12, I'd say. This adds some "grunge" to the image.
Add the first Levels layer. On the RGB channel, use these values: 0/0.40/255 and 0/230. This will make the whole image dark. Mask it off the people and the ground to your taste. You can see my mask in the screenshot.
Finally, add another Levels layer and pull the black Output slider in to about 35 (or to your taste) for the matte effect.