Holder of the lease, payer of the rent, and responsible for all production on held land, the head of a household controlled all economic functions of their medieval or early modern English holding.
In noble households, the head of the household was the noble himself. His title ensured that he had power not only over his individual household (his family, servants, and various staff), but also the surrounding regions, where he was likely to act as landlord. His wealth gave him economic control over the smaller households of which he was landlord. Simultaneously, however, he was expected to provide for those in his own household and to be a good landlord to those households under him. This may or may not have actually been the case: with the arrival of profitable sheep farming and the subsequent advent of land enclosure , many landlords used any means necessary to drive their tenants off the land.
In the smaller holdings, the head of the household was generally only the head of the family: the father and husband. He held authority not by noble title, but by holding the lease for the land which sustained his household. He may have bargained for this lease himself, or inherited it from his father. But in order to hold any economic power, the lease was of vital importance. Land was both money and food at this time; if one could not get a lease for a holding, one was generally screwed out of an economically independent life. If one had no holding, one could not, for example, get married: one had no hope of supporting a wife, not to mention children. In holding the lease, the head of the household provided the economic benefits of land not only for himself but for his family. If he lost that lease, the entire household was, as previously mentioned, screwed.
For this reason, the head of a small household needed to be as shrewd, as productive, and as prosperous as possible. Landlords were chafing at the bit to turn out any tenant they could, so as to convert the farmland into pasture; the nobles did not need to use all their land for sustenance. If you could not pay the skyrocketing rent, if the copy (the written record of lease) to your hold had been destroyed, or if you only had a customary hold (with no written record), you were, again, screwed.
Incidentally, this has been a nodeshell rescue.