The first true King of England was Æthelstan of the House of Wessex. Æthelstan is arguably more important than Alfred the Great (his grandfather) and William the Conqueror in that he united the disparate Saxon kingdoms of England into one nation (Alfred was the King of Wessex, not England). He is the first monarch to not only create the title of King of England but who was able to claim to be King of Britain.
The 12th century chronicler, William of Malmesbury, wrote that “no one more just or more learned ever governed the kingdom”.
"This royal throne of Kings, this scepter'd isle,
This Earth of majesty, this seat of Mars,
This other Eden, demi~paradise,
This fortress built by Nature for herself,
Against infection and the hand of war,
This happy breed of men, this little world,
This precious stone set in the silver sea,
Which serves it in the office of a wall,
Or as a moat defensive to a house,
Against the envy of less happier lands,
This blessed plot, this Earth, this Realm,