oh come on, you dont say "behind the gate" when your nowhere near it.
Of course we werent there so only have the account to go on, the google maps shot a typical rural scenario. No pavement so no public footpath just grass verge and hedgerows. It sounds like the OP was setup between the gate and the road on the grassy verge or in the gateway however you want to call it.
He assumed that because he wasn't "in" the field (on the other side of the gate) he was on public land and was arrogant about saying so (the very opening remark to the conversation was sarcastic). Now unless he was actually in the road which I doubt as he woudn't want his gear smashed by a passing car. Given that situation (which is how it reads to me) the farmer was perfectly entitled to not give permission.