We need to bear in mind that some of the master tapes for Harriott sessions like 'Hum Dono' may no longer exist (I've certainly heard no definite confirmation that they survive in master form - no legit 'Hum Dono' issue has as yet appeared).
Most of the Harriott UK Columbia sessions were privately produced by Dennis Preston at Lansdowne Studios under the 'Lansdowne Jazz Series' then issued by the likes of Pye/Nixa and UK Columbia (now owned by Universal). Some of the Columbia material from the 60s (e.g. Neil Ardleyalbums) was recently re-issued by them under the 'Impressed Re-Pressed' imprint but it was apparently like getting blood out of a stone after the first batch came out around the time of 'Jazz Britannia'. Other UK Columbia releases have been put out by BGO (e.g. the Rendell/Carr Quintets).
Redial put out a couple of the Joe Harriott sessions on CD ('Free Form' and 'Abstract') but as yet no sign of 'Movement', 'Southern Horizons', 'High Spirits','Personal Portrait' (the one with David Mack), various EPs or the Amancio d'Silva collaborations.
Maybe Mosaic can pull off a miracle by talking Universal into it. Certainly hope so - I would pre-order in a flash.