Ref the original topic.
There are a number of 'weasel words' here. This is probably the kind of terms that would be thrashed out in court.
'Surveillance' - Perhaps aerial photography for purposes other than gathering information or watching people (stalking/paparazzi) are exempt.
'Aircraft' - At what point does an model become a craft.
'Unmanned' - There will probably be some distinction between unmanned and radio control. Perhaps having the technology to fly further than line of sight. I.E. some telemetry, or TV with a pilots eye view beamed back to an operator.
Not sure about the others but a model plane effectively becomes an aircraft when it needs a CAA exemption certificate. This is determined by its weight. The exemption is from Air Navigation Orders applicable to aircraft.
HTH.