All good. I've raised one question, so please see that before merging, and generally don't forget to mark migrated methods as 'daskified' via the decorator of that name to help us keep track of the migrated methods in the Data module itself (to complement the big table in #295); ideally add in those decorators on each PR, including this PR, before merging. Thanks.

There is now a merge conflict to resolve, but otherwise this is all good to merge.