Was a "Bomber" Superimposed onto Metropolitan Police Surveillance Camera Photo?

I found this article....I don't know what to think. I enlarged the photo and it does look like it has been faked but why?
what do you guys think?

http://www.legitgov.org/cctv_image_o...ts_240705.html

yeah, his arm looks like it's behind the rail that's behind him...here's a larger picture of it...i think the 'terrorists' were patsies who thought they were part of some anti-terror drill.