@Heart of Storm, I have to assume the air rifles being spoken about by the gun forum people for foxes are FAC (Firearms Certificate) rifles over the 12ft/lb UK limit. I do HFT air rifle shooting and have several full limit rifles and there's no way I'd shoot a fox with one. I've shot pheasants, rabbits, pigeons, rats and crows with them, but definitely not a fox. If you were a supremely good shot you could perhaps get it through they eye socket for a clean kill, but I wouldn't try as it's far more likey to just injure it, which is unnecessarily cruel even if they are stealing your chickens - it's just doing its natural foxy thing.
For foxes you need a shotgun, proper rifle (a .22LR will do it no problem), or a ponce in a red coat on a horse. MedMos is probably right that a fairly powerful crossbow would be alright - plus you can buy one in the UK legally with no restrictions on power - but if you get one then please practice at various ranges for a good time first so you are confident you can get a kill shot with one bolt.
In vegetable news - my carrots are trolling me. Huge, beautiful bushes of green and I think "wow, the carrots attached to that must be amazing!". Not one of them more than 3" long
For foxes you need a shotgun, proper rifle (a .22LR will do it no problem), or a ponce in a red coat on a horse. MedMos is probably right that a fairly powerful crossbow would be alright - plus you can buy one in the UK legally with no restrictions on power - but if you get one then please practice at various ranges for a good time first so you are confident you can get a kill shot with one bolt.
In vegetable news - my carrots are trolling me. Huge, beautiful bushes of green and I think "wow, the carrots attached to that must be amazing!". Not one of them more than 3" long