[Clive] James takes a great deal of typically footnoted factual clarification "out of the basement" and interpolates it into the verse of the poem itself, maintaining that "English needs less room than Italian" and so can accommodate additions without slowing the pace.
The extra room is created because he alters Dante's famous rhyme scheme. "The first thing I had learnt," he tells us, "was that a strict terza rima was out of the question" (although Sayers managed it for all three volumes of her translation, "despite the alleged impossibility"). He adopts instead a loose quatrain metre, "augmenting" it as warranted. And with the extra syllables and half-lines this creates, he's able to insert quick clarifications as they crop up.
from The National: Clive James's translation of Dante without annotations is earnest but confusing