It is possible that the 'drones' are being classed as 'Small Aircraft' in which case there are specified rules in the ANO which apply. These can be up to 150Kg in weight with the authority of the CAA and require the issue of an exemption if it is over 20Kg. The CAA do however state that exemptions are unlikely to be issued except for a specific flying site, which would be no use for a tactical application.
However, if a weight of less than 20Kg, then only the following seems to apply:
Article 74
“A person shall not recklessly or negligently cause or permit an aircraft to
endanger any person or property.”
All model flying activity is controlled by this article of the ANO and it is important that the operator of any model aircraft should bear this in mind at all times.
If they have an exemption to be between 20Kg and 150Kg, then the following restrictions are then in force:
Article 73
“A person shall not recklessly or negligently act in a manner likely to
endanger an aircraft, or any person therein.”
Article 73 refers to people in an aircraft endangering the aircraft or persons therein, whereas Article 74 refers to persons outside aircraft endangering aircraft. Obviously only Article 74 can apply to a model aircraft. However, technically Article 73 does apply to models over 20 kg.
Article 98
Article 98 contains additional requirements to fly model aircraft safely.
Article 98 states:
“(1) A person shall not cause or permit any article or animal (whether or not
attached to a parachute) to be dropped from a small aircraft so as to
endanger persons or property.
(2) The person in charge of a small aircraft which weighs more than 7 kg
without its fuel but including any article or equipment installed in or
attached to the aircraft at the commencement of its flight shall not fly
such an aircraft:
(a) unless the person in charge of the aircraft has reasonably satisfied
themselves that the flight can be safely made;
(b) in Class A, C, D or E airspace unless the permission of the appropriate
air traffic control unit has been obtained;
(c) within an aerodrome traffic zone during notified hours of watch of the
air traffic control unit (if any) at that aerodrome unless the permission
of any such air traffic control unit has been obtained;
(d) at a height exceeding 400ft above the surface unless it is flying in
airspace described above and in accordance with the requirements
thereof;
(e) for aerial work purposes other than in accordance with a permission
issued by the CAA which may be issued subject to such conditions as
the CAA thinks fit.”
There are also UAV documents from the CAA since the small aircraft will be conducting aerial work possibly, but I need a bit more time to track them down !!