Eventually , the market evolved into a national one driven by London and other growing cities .
The next stage of development was trading between markets , requiring merchants , credit and forward sales , knowledge of markets and pricing and of supply and demand in different markets .
The market evolved into a national one driven by London and other growing cities .
The next stage of development was trading between markets , requiring merchants , credit and forward sales , knowledge of markets and pricing and of supply and demand in different markets .