Hi, brianmelendez, I think that this interpretation of the East Grenwich thing is not correct.
I respect Niall Ferguson as an historian, but I'm a bit dubious of the claim being put forward that as a matter of law, the British North American colonies were deemed to be part of Kent.
It's correct that this term was used in land grants in the British North American colonies, but it wasn't just in the BNA colonies. Lands were held all over England "in free and common socage "as of his majesty's manor of East Greenwich". That didn't mean that those parcels of land were henceforth part of Kent.
What was going on here is more a matter of land law than of representation. Originally, during the feudal period, all land was held of the king, through feudal service, or by sub-infeudation from the king's great feudal magnates to their followers.
There were different types of feudal tenure, such as knight-service, frankalmoin and serjeantry. All of these involved some sort of personal service from the tenant to the feudal lord.
For instance, knight service was the type of tenure for the great lords and some of the lower lords and gentry. The tenant who held by knight-service owed various military duties to his feudal lord, such as a duty to provide men to support his feudal lord in military actions. Over time some of these feudal obligations were translated into various fines and other monetary obligations (e.g. to contribute money to celebrate the knighting of the feudal lord's eldest son, or to contribute to the marriage of the feudal lord's eldest daughter), but the bottom line was that a tenant holding by knight service could be called on to provide services or money to his feudal lord. This meant that knight-service tenure could have quite expensive obligations, often on short notice. It was a type of land tenure that was still tied to a personal relationship of some sort to the feudal lord, rather than outright ownership by the tenant.
However, there was another type of tenure, that of common socage. It was a feudal tenure, but originally it was held by individuals quite low in the social hierarchy, who were not expected to participate in military activity, but to till the soil. Their feudal duty was simply to provide agricultural produce or cash to the feudal lord, who would use it, in theory, to finance the military service he owed to his feudal lord.
As time passed, free and common socage became more and more popular as a form of land tenure, because it was the most flexible. The tenant held the land in exchange for money, not personal service. The land could be more easily alienated than land held under the other types of service, which in turn helped as England's social structure moved away from feudalism and towards a more market driven economy. As a result, individuals who acquired land from the Crown began to request that it be assigned as free and common socage, rather than one of the other feudal tenures.
So why East Greenwich? Because the medieval common law didn't operate on legal principles, but on legal precedents.
If the King granted Blackacre in Yorkshire to Sir John, to be held "in free and common socage, as of our Manor of East Greenwich", the legal effect of that was that Sir John held Blackacre on the same legal terms as applied to East Greenwich. If a dispute arose about the terms of the tenure, the dispute could be resolved by asking how the tenure of East Greenwich operated in a similar case.
It didn't mean that Blackacre was suddenly no longer part of Yorkshire but of Kent, nor that Sir John voted for the MP for Kent rather than Yorkshire. It just meant that his legal obligations for Blackacre were the same as the legal obligations of the tenant who held the manor of East Greenwich.
Then, when the King began granting charters for land in the new world, it made sense to use this same system of land tenure. Land in England's North American colonies would be held in socage tenure. The tenants wouldn't owe any feudal services; at most, they would have to pay a cash rent from time to time to the landlord.
Over time, free and common socage evolved into what is now known as tenure in fee simple. Technically, all land in the English common law system in fee simple is held by the owner by a grant of the Crown, an extremely attenuated remnant of feudalism.