Great Britain was once the world's greatest superpower and yet managed to transition without becoming fascist. I think that history actually shows a diversity of scenarios.
If your going to define fascist as something that apply's to more than just Italy then, Great Britain got a lot closer to fascist than you might suspect. For example, agricultural subsidies use public funds to prop up private enterprises which is fascist. They also went into public surveillance, and indefinite detention without trial etc.
PS: It's a slippery term, but originally it had nothing to do with Germany.
PS: It's a slippery term, but originally it had nothing to do with Germany.