class mobility through marriage during the Restoration

Gentleman or gentlewoman is not, strictly speaking, a class. Either one is common, or one is noble. A gentleman or gentlewoman would be a product of one's wealth, and judging that wealth is a superficial exercise. For example, see Becky Sharp and Rawdon Crawley in Thackery's Vanity Fair, and "living on nothing a year." If one has sufficient wealth so as not to need to soil one's hands in getting one's living, one can be considered gentle.

Strictly speaking of the class structure, if one is common, one can still be a gentleman or a gentlewoman if one has the means to live that well. If one is noble, one can fall below the means to live as a gentleman, but one remains noble. Generally speaking, one who is noble-born, and reasonably well educated in the sense of being taught how to behave when one was a child at home--such a one will be taken for a gentleman so long as one is reasonably attired, even if the clothing is shabby.

I am assuming that by the restoration you refer to the restoration of the Stuart monarchy in 1660 (i know of no other restoration if one refers to English history). "Class" mobility entirely depended upon whether or not one were noble, or would be ennobled. If Charles and James Stuart owed you money (quite a considerable body of people) or you had been a public supporter of their Father King Charles I, the chances of being ennobled, if one were not yet noble, were pretty good.

Economically, the times were very fluid, especially during the Anglo-Dutch wars. The Royal Navy, at least nominally under the command of James Stuart, actively protected English commerce, while the Dutch and their erstwhile French allies, attacked the Royal Navy, rather than English shipping. So English commerce prospered in the 1660s and -70s.

One result of the Anglo-Dutch wars was the seizure and cession of New Holland to England. New Holland was the former Dutch North American colony, as well as the former Swedish North American colony which had been taken over by the Dutch. Upon their cession to England, they became the colonies of New York (James Stuart was the Duke of York), New Jersey (upon the execution of King Charles I, Charles Stuart the younger was sheltering on the island of Jersey, and was recognized as King Charles II only on the island of Jersey--this was pay back, once again), and what became Delaware was originally "leased" to William Penn, and administered as a part of the Pennsylvania colony. Once again, this was pay back, because Charles and James Stuart owed at least 15,000 pounds sterling (possily more) to William Penn's father, and repaid that considerable sum by giving William Penn that huge colony.

There was a good deal of economic mobility, therefore, during the reign of King Charles II (1660-85), and that would determine whether nor not one were considered a gentleman. Marriage only entered into such a calculation to the extent that money were involved. If marriage brought money, one might set up for a gentleman. If one already had money, and managed not to lose it or squander it, one would be considered to be and treated as a gentleman.

For a reliable and readable life of Charles II, see Royal Charles (title under which it was published in the United States) by Antonia Fraser. For economic fluidity in Restoration England, any number of survey histories of the period (however well or badly written) will serve. For the Anglo-Dutch wars in the reign of Charles II, and particularly the differeing attitudes toward national merchant fleets, see The Influence of Sea Power upon World History, 1660-1783 by Alfred Thayer Mahan. For the Dutch and Swedish North American colonies and their English successor colonies, once again, see any number of survey histories on the period, particular to North America.

If one were "gentle-born," whether or not one continued to be considered gentle depending on one's financial status--it has nothing to do with class, strictly speaking. Hence my reference to Vanity Fair, which while not about the Restoration, was very much about the idea of "gentility." Becky Sharp was not "gentle-born," and Rawdon Crawley was. Having married against the wishes of Rawdon's Aunt, from whom he had expectations, and therefore having lost those expectations--after Waterloo, when Rawdon sold his commission, they didn't have two shillings to rub together. However, they were able for a period of many years, to give the appareance of having money (hence Thackeray's phrase "living on nothing a year") and therefore were accorded the respect and extended the credit which was afforded to those considered to be gentlemen and gentlewomen. That is the entire burden of Thackeray's novel--the reality or the appearance of wealth, or the lack thereof--and although it takes place more than a century and a half after the Restoration, the rules of the game are the same.