The EMI catalog (with some exceptions, like the Beatles, and Jethro Tull, and some of the Harvest artists like Barclay James Harvest, ELO and Pink Floyd) now belongs to Warners, so these would be Quadio releases, if anything. When UMG absorbed EMI in the early 2010s, EU regulators stipulated that they had to sell off 1/3 of their combined music catalog to other established labels as part of anti-trust/competition compliance, and that's how Warners got the EMI titles. When you subtract the aforementioned artists that weren't part of the deal, there aren't that many quad-related items of interest: Mandingo (four albums), John Keating (four albums), Marvin, Welch & Farrar's Second Opinion are probably the best of the lot, but beyond that does anyone want to pay 25 bucks for a reissue of Manuel and the Music of the Mountains, or Ron Goodwin In Concert?
As for the Pye catalog, it is controlled by UMG, but (as I think Mike mentioned on his Life in Surround interview) most of the quad masters are no longer with us - and he would be in a position to know as he worked for Pye/Precision Tapes in the mid-80s. There may be a few stragglers, and perhaps there are safety copies in Japan for the handful of releases that came out there, but with time as a finite resource and better stuff still available from other labels, I can't imagine these are too high on his "to-do" list.
As for the Pye catalog, it is controlled by UMG, but (as I think Mike mentioned on his Life in Surround interview) most of the quad masters are no longer with us - and he would be in a position to know as he worked for Pye/Precision Tapes in the mid-80s. There may be a few stragglers, and perhaps there are safety copies in Japan for the handful of releases that came out there, but with time as a finite resource and better stuff still available from other labels, I can't imagine these are too high on his "to-do" list.