I'll tell you another seminal 70s band: Motorhead. Directly inspired ALL thrash metal and speed metal. Anthrax, Metalica, Megadeath, and Slayer all freely praise Motorhead as the start of it all.
And of course: T Rex and Thin Lizzy are game changers as well, although I would say they share one spot and are kind of linked.
You also have to count E.L.O. who created a sub-genre that includes Queen and leads to shit like Muse in todays world.
Add in Elton John, just because his 71-76 catalog is just some of the best shit to ever come out of Blighty.
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I really wanted to go to that Bukake because I thought for sure that you were going to be on the receiving end. - Ryan Knox to Jeff Steward