Lyric discussion by yurig 

what does she mean the thames river was hastily sold for nothing?

The line about selling gold hastily for nothing is an attack on Gordon Brown who did exactly that while he was Chancellor.

From Wikipedia:

@yurig She said it was glistening like gold hastily sold for nothing. The Thames wasn't sold. The gold sold for nothing is a simile for the way the river was glistening,

@yurig London was the hub and nerve centre of the British Empire. We plundered the the riches flowed back to London like a golden river.

As some others have said this is also a rebuttal to Gordon Brown's sale of some of Britain's gold reserve. He was criticised for selling too much, too soon and therefore deflating the price.

An error occured.