Keith Roberts was a sadly under-rated British sf writer, and, sadly, he knew it. As his Wikipedia page says, when he dies in 2000 "obituaries recalled him as a talented but personally 'difficult' author, with a history of disputes with publishers, editors and colleagues." His SFWA obituary page does confirm this.
Looking at his Fantastic Fiction page, I see he did get nominated for the Hugo and Nebula, as well as other major sf awards, which can't be bad, though my favourite, "Pavane", set in an England where the Spanish Armada had succeeded, didn't itself feature in that list, perhaps because it was made up of a number of stories. There is a lengthy review here.
Keith Roberts was a talented artist, too, and produced many covers for the Compact-era New Worlds and Science Fantasy/Impulse - he also became Impulse's editor, after working with Harry Harrison on the title. He is certainly an author worth seeking out, and was a major voice for UK sf and fantasy, alongside Aldiss, Ballard, and Brunner.
Keith Roberts 1935-2000