Don't understand the debate really.
HO Guidance Para 1.3.
"Low powered air weapons are not licensed in England and Wales unless they are of a type declared specially dangerous by the Firearms (Dangerous Air Weapons) Rules 1969 but there are restrictions on their sale. An air weapon is "specially dangerous" if it is capable of discharging a missile with kinetic energy in excess, in the case of an air pistol, of 6 foot lbs or, in the case of other air weapons,12 foot lbs."
So no licence is required for sub 6/12 airguns [regardless of the action type].
While the S5 definitions of prohibited firearms might be interpreted to include semi airguns, were this so then possession would require a S5 licence, and the document has earlier and unambiguously stated that licences for such airguns are not required.
The debate seems to hinge around reading one part of legislation in isolation from the rest of the relevant material.
Also this nonsense about rifled vs smooth seems to be pure invention. The only area where smooth/rifled this comes into play is an exemption which allows smooth bore muzzle loaders to be held on S2 even if firing a single ball or bullet.
Taking a simple example from motoring law, it is illegal to travel in the wrong direction in a one-way street. Elsewhere we are required to obey the instruction of a police officer directing traffic [who might in fact be directing us against a one way system because of a road closure for e.g.]
True freedom includes the freedom to make mistakes or do foolish things and bear the consequences.
TANSTAAFL