Jack Douglas: "We asked Neal to do stems of all his mixes, and in the case of 'Legendary Child' we then took these stems to Spitfire, which is in Warren's back yard, and did the rest of the mix work there. There also were times during the mastering process when we used stems to tinker with stuff". Full story here.
These mixes were never released commercialy and they do sound good, so check 'em out!
Here's some pictures of the disc and insert: