Beware of anything for which there is official guidance!
The CAA has been writing guidance for UAV operations since 2001. The current document is "CAP 722: Unmanned Aircraft System Operations in UK Airspace - Guidance". This includes the statement that, outside controled/segregated airspace, UAV's should not be operated above 400'.
The reality of autonomous operations (i.e. UAV's, UACV's, drones, etc) is that they'll become increasingly pervasive across the World. Not only are they use by the military for offence/defence (e.g. Reaper and Predator) but also by relief agencies for surveilance and will be increasingly used for things like domestic crop monitoring (probably people monitoring too!).
Ever since there was the debate about ADS-B vs transponders and the expansion of "controlled airspace" the term "interoperability" has been adopted to reflect the (current) constraint for drones to properly operate a see and be seen principle for VFR when operated beyond visual range of its operator (or autonomously). The only thing that keeps us away from seeing the prophesy of Terminator coming true is that the computer network to manage the devices isn't called SkyNet. :-( Meanwhile, lookout, lookout, lookout!