Verrrrry hinterestink!
This style of vase - masses of copper aventurine on a mottled coloured background, pulled into spirals was also the style of stuff he was making a lot while working with John Deacons and Willie Manson in his recent retirement years - he also made a lot of Vasart-style Tulip lamps in this exhuberant style - I had been under the impression it was a "diversion" into Ysart-style glass he'd been getting into - I hadn't realised this was also a Caithness style!
I imagine yours, as a limited Edition Caithness piece, is rather unusual, but pieces like this may well turn up - but not marked as Caithness and not of a Caithness origin.