Richard as Landlord

I would like to understand better one of Gaunt's criticisms of Richard (we are back in Shakespeare now, in Act II, scene 1).

In his final speech, Gaunt describes England as being "leased out...like a pelting farm. England...is now bound in with shame, with inky blots and rotten parchment bonds."

Then later, Gaunt says

Why, cousin, wert thou regent of the world,
It were a shame to let this land by lease;
But for thy world enjoying but this land,
Is it not more than shame to shame it so?
Landlord of England art thou now, not king:
Thy state of law is bondslave to the law

To what is Gaunt referring? In what way is Richard letting England by lease and in what sense is he landlord, not king, of England?