The British discussion tends to focus on passenger power. It is true that the New York Central was unable to find much advantage in a pair of E-7 diesels over one of their super 4-8-4s. In North America, however, that's not the governing factor. No steam locomotive, not the Norfolk and Western A, neither the Union Pacific Challenger nor the Big Boy, not even the Boston and Maine R-1, could resist the power of four portholes.
Raimund Whynal photograph courtesy Trains Online
The interesting counterfactual is, what if the British had asked Electro-Motive or Nohab to scale the F-7 down to fit their loading gauge?