The Weasel is fond of saying that steam engines come at steam engine time. So, we need a combination of technology (metallurgy having advanced to the point that you can make a boiler that won't burst under pressure), a killer app (pumping water out of mines) and a set of technoeconomic innovations that make it easier to bring together clients, entrepreneurs, inventors, investors and workers. A fourth requirement would be the set of inventions related directly to how the steam engine works.

They used to say that by the time Time or Newsweek had something on the their front cover that thing had already passed its peak. Perhaps London was swinging less after that famous 1966 Time cover than it had been a few months earlier as things shifted to San Francisco. But then somethings are never going to pass their peak.