Concerning the noveau riche and fashion; wouldn’t their status preclude good taste regardless of how “in fashion” or “fashion forward” they are? I can’t help but picture a merchant’s wife wearing the queen ‘s brand new style and the style being immediately declared out of fashion, the bourgeoisie making it bourgeois.

That can happen, but it’s more of a gradual thing:

“Anne the queen wears yellow, as she did when she first appeared at court, dancing in a masque: the year, 1521. Everyone remembers it, or they say they do: Boleyn’s second daughter with her bold dark eyes, her speed, her grace. The fashion for yellow had started among the wealthy in Basle; for a few months, if a draper could get hold of it, he could make a killing. And then suddenly it was everywhere, it sleeves and hose and even hair-bands for those who couldn’t afford more than a sliver. By the time of Anne’s debut it had slid down the scale abroad; in the domains of the Emperor, you’d see a woman in a brothel hoisting her fat dugs and tight-lacing her yellow bodice.” 

Hillary Mantel, Bring Up the Bodies

If the nouveau riche instantly devalued fashion, they wouldn’t be a social threat to the old aristocracy – the terrifying thing for the nobility was the way that they could blur the lines between noble and commoner, pass among the former while still being the latter, confusing what ought to be the most basic (and to people’s thinking, natural) visual distinction. 

But the ability of the nobility to fight back to declaring things out of fashion is that time and distance conspire against them: there’s no group DMs or Slack channels or (going prehistoric here) email listservs to coordinate these decisions – eventually, there will be women’s magazines and the like, but that comes along a bit later and has a bit of a problem of needing to sell to mass, and thus, common audiences – you have to write letters and for a lot of this kind of stuff you really need to get everyone together in person, and that can be difficult. (Versailles was such a help in that regard.) 

Because of this, there was this liminal space, whereby a sufficiently fashion-forward/culturally capitalled bourgeois could penetrate aristocratic spaces and snatch up titled husbands and wives before being detected, which is why it became such a major topic of literature. 

Anguy won 10 000 golden dragons on the Hand’s tourney with his archery skills. If he had more modern-day senses and long-term thinking about his life (no offense, Anguy), then what could a man of the smallfolk have done with this amount of money to improve his life in the long term? What are the options?

Great question! 

I would say that his best bet for upward social mobility is to find an heiress of a poor noble family and marry his way into a title (either that of a landed knight or a petty lord) – the fact that he has a lot of cash on hand means that he can skip a lot of the steps along the way that people in medieval societies attempted to climb the social ladder. It would probably also help if he were to serve with distinction in war and get himself knighted* to belt-and-braces his drive for noble status, and given his superlative skills as an archer that wouldn’t be hard. 

* hell, he managed this in OTL (in a fashion) despite having wasted his money. If Ser Anguy survives the BWB, there’s no reason he couldn’t have a decent career as a sworn sword or household knight (and even a tourney knight, if he can find enough tourneys offering archery prizes). 

Next best, he could marry into a merchant family. This would advance him up to the status of burgher, and I would imagine there would be a lot more merchant families who’d be quite happy with such a large injection of capital and who’d be much less snobbish about his background than the minor nobility would be. My hesitation here is that, while Anguy is a perfectly nice young man, he doesn’t seem to have much of a head for or experience in business. Might be happy as head of security, maybe.

Another possibility is creating a sellsword company; he certainly has the up-front liquid capital to hire several hundred skilled archers and sell their services. Again, I don’t know necessarily that Anguy has the necessary head for military command or small business management, and mercenary work has all of the risk of social mobility through military service with less of the possibility of advancing into the nobility. Also, it would probably mean spending a lot of time in Essos, and Anguy might not like living abroad.