Some corrections to my last posting (I should have read the introduction more carefully): the publisher of Queen Mab was Shelley himself, and he distributed only 70 copies to aristocratic acquaintances. He’d written it was he was 19.
However, pirate copies some years later got the poem widely known to a working class audience, with the result that it eventually became a bible for the Chartists.
The notes include the text of his pamphlet, ‘The Necessity of Atheism’, for which he’d been sent down from Oxford in 1811.
It seems Shelley didn’t know Blake’s work.