The transition to Diesel wasn't just the result of oil lobbying- the steam loco is sadly inefficient, and it's difficult to see how even the best engineering brains available could have made it much better. Even with Porta's innovations, the diesel is far more attractive, especially where duty is intermittent.

That's not to say I prefer looking at Diesels to steam...

As for Bulleid, he was a bit gone with the fairies by that time, and his turf- burner could't hope to compete even with the botched first attempt at Dieselisation in Ireland. Crossleys indeed!