For the most part its the same in the UK Fujii.

And long may it continue.

I'm not joining the bush Lawyer debate on who owns what above an owners property but in Australia you cannot fly an unregistered aircraft or fly unlicenced over private land. Ultralights have simular rules I believe.

I am pretty certain you can fly tethered without a license or the thing licensed in the UK. The nutters that do home built helicopters do that and also some balloons.

But as Fujii says big big country and as long as nobody see's you.

But I add the next clip as a point of warning.

Pilotage

Not quite correct(ask Korean Air!)

Chicago Convention Article 6: (Scheduled air services) No scheduled international air service may be operated over or into the territory of a contracting State, except with the special permission or other authorization of that State.

That there's the Gotcha !
Some years back, I read an article in an Aviation Mag. concerning an Aussie pilot, out in the Bush, transiting a remote property. Looking down, he saw an odd-looking light aircraft flying low and somewhat erratically. "high-flyer " noted it had a Registration and copied it...... the upshot was, the aircraft had been written-off and sold as scrap. Mr Outback bought it and grafted in a Rover 3.5 Litre V-8 car -engine, cooling -system and ancilliaries.....nail a prop on it Cobber, and she's good to go ;)......Except "high-flyer " saw and reported his unexpected encounter and poor old Mr. Outback was "done" for it.....some would say he was saved from himself, but the Wrights got away with it, and look where that's led us!

In England since the battle of hastings in 1066, when William 1st stole the country from the people, only one person owns all the land, the Crown. All anyone owns is the freehold of the land surface, which means the minerals and air are ownered by the goverment. So if the goverment says you can fly through it you can.

I think you chaps have missed the point here: OP said "Can I fly unlicensed, unregistered aircraft above private land. " The answer is NO and NO not legally (even test flights need a permit) Even if your Aircraft was kosher, the are minima you need to consider especially if you don't own the land,.. that is (in NZ anyway) 500ft above structure (car, tractor, boat, house, picnic table) and 500ft either side. I have known two chaps be busted for this so watch out, if they have a camera and or video, get a lawyer or get hold of AOPA. In any case what the OP was asking is slightly alarming, but hey either way the Wright brothers win, or Darwin does.

Re the "can" part of the question. Yes you can. The same as murder, you can but is is illegal. Secondly, what type of aircraft, the question didn't say. It could be a para glider with a motor. Not registered and there is not a licence as such.