Read the Deer Act section 1.3. Also being in a public place with a firearm is not an offence if there's a reasonable excuse, which there clearly is in this case, ALL the way from where the shooter lives/keeps his gun and onto his "permission".
I already answer your question at post #34
The Firearms Act was amended to get by the public places clause, like Forestry commission woodlands which are all under CRoW and allow the public free access. Without this condition you would be breaking the law by having a firearm in a public place, loaded or not but now you have just reason under the act.
Carrying firearms in a public place (section 19 of the 1968 Act)22.15 Section 19 of the 1968 Act makes it an offence to have in a public place without lawful authority or reasonable excuse (the proof of which lies on the accused) a loaded shotgun, an air weapon (whether loaded or not), any other firearm (whether loaded or not) together with ammunition suitable for use in that firearm, or an imitation firearm.
22.16 Section 57(6) of the 1968 Act includes a definition of “loaded” in relation to shotguns and air weapons. An air weapon is to be treated as loaded if there is ammunition in the chamber or barrel or in any magazine or other device which is in such a position that the ammunition can be fed into the chamber or barrel by the manual or automatic operation of some part of the gun or weapon.185 Guide on Firearms Licensing Law
22.17 The definition of a “public place” in section 57(4) of the 1968 Act is the same as that in section 1(4) of the Prevention of Crime Act 1953, specifically “any highway and any other premises or place to which at the material time the public have or are permitted to have access, whether on payment or otherwise”. For Scotland, the word “highway” in the definition of “public place” in section 57(4) has been deleted and replaced by “road (within the meaning of the Roads (Scotland) Act 1984)”.
I think in answer to the original question if a person stood in a field where he wasn't the holder of the shooting rights, on a public footpath with his gun resting on the stile pointing over his permission then according to the law he would be guilty of armed trespass. If you shoot from a path situated on somebody else’s land (regardless of who owns
the rights to shoot on the land you are shooting into) it is taken to be armed trespass which is a criminal offence. It also says, Persons using a right of way are prohibited from loitering or using it for purposes other than a reasonable use.
Good question at the start but only one answer, don't do it and risk your licence as anything against you relating to firearms will result in you losing it straight away or when it comes up for renewal and the question have you been convicted or cautioned for any offence.