"Or stole it: William the Bastard gifting our land to his henchmen, or the theft that occurred during the highland clearances, plantation of Ulster, or the acts of enclosure. - Sugarfoot Jack

Duke William of Normandy:
When King Edward died at the beginning of 1066, the lack of a clear heir led to a disputed succession in which several contenders laid claim to the throne of England.

1: Duke William of Normandy's claim to the English throne derived from his familial relationship with the childless King Edward the Confessor. King Æthelred II of England having married Emma, the sister of Richard II, Duke of Normandy in 1002. So William the Bastard was a blood relation to Edward the Confessor.

2: Earl of Wessex Harold Godwinson, brother-in-law to the late King Edward the Confessor. Harold Godwinson was not a blood relation.

3: King Harald III of Norway otherwise known as Harald Hardrada - His claim to the throne was based on an agreement between his predecessor Magnus I of Norway, and the earlier King of England Harthacanute, whereby if either died without heir, the other would inherit both England and Norway. Pretty shakey claim

So as far as the succession went after the death of King Edward the Confessor there was only one claimant who was a blood relative. So nothing was stolen at all although both Harold Godwinson and Harald Hardrada did attempt to steal a Crown. Damned right that the lands of those who opposed William be forfeit and gifted to William's supporters, that was how things worked, serfs and slaves under Saxon Lords became serfs and slaves under Norman Lords so no change there.

Highland Clearances:
I would be interested in knowing when you think that they started, and who it was that started them. The land belonged to the Clan Chief and he dictated who lived on it and by it. The clearances by and large were economic. Around the same time that the "Highland Clearances" were beginning the "Clearances" in the Borders were coming to an end. The new King who jointly sat on the thrones of both Scotland and England wanted to get rid of the trouble-makers in his "middle-shires" which rather neatly leads us on to -

The Plantation of Ulster:
During Elizabeth the First's reign, Chief O'Neil had tried his very best to make Ireland a colony of Spain with himself as its Viceroy. He rebelled against Elizabeth and had to flee. In 1588 there had been the scare with the Armada so mindful that in Ireland trouble might be stirred up by Spain, King James I and VI saw an ideal opportunity to kill two birds with one stone. He moved the trouble makers from the Anglo-Scottish and planted them in Ulster and gave them rebel lands. If there was one thing King James knew about his borderers they would fight like hell to hold what they had been given (After all they had been doing that amongst themselves for over 350 years without a break).

Acts of Enclosure:
These began in the 13th Century and continued through Tudor times and were had their final spurt between 1760 and 1820. In total they affected about 18.5% of the land in the country. Oddly enough Sugarfoot the worst culprits were not the rich landowners, the most rapacious exploiters of the practice were minor land owners and tennant farmers. Had the land not been enclosed the country would have starved, the Agricultural Revolution would not have happened and the Industrial Revolution would have been stunted. Ever heard of a thing called progress?

As to what the Queen "owns" Sandringham and Balmoral were bought and paid for by Prince Albert, he paid the going rate at the time and worked damned hard at building both estates up.