The question of "why not USB" is relevant regardless of what happened. Having sensitive printed documents traveling about like that isn't very secure. But I'm

The question of "why not USB" is relevant regardless of what happened. Having sensitive printed documents traveling about like that isn't very secure. But I'm half joking about it being a dead drop. (Only half because the UK has been very deeply penetrated by foreign intel operations before) One explanation for USB vs. printouts, I guess it would depend on the security measures in place. The ability to use USB drives could be disabled in various ways to prevent bulk data removal while printing was still allowed. Or the reports were centrally printed out and distributed to various recipients, so it was never digitally accessible to the person who lost it.