The Floyd's influence is huge. From Robyn Hitchcock through Flaming Lips and on to shit like Radiohead and Coldplay.

Although not really a band like the big four mentioned above, I would have to add David Bowie as one on the most influencial of the 60s-70s British rockers. The Spiders From Mars/ Hunky Dory/ Low period Bowie essentially laid the groundwork for 90s alternative rock. Smashing Pumpkins, Nirvana, Pixies, Soundgarden, Jane's Addiction, etc are direct descendents of Ronson/Bowie.

And if you want to hear the album that inspired the Black Crowes and Kings of Leon and all that stuff, listen to Jeff Beck "Truth". One of the best rock albums ever!