Consider it solved.
The latest Mystery Market sale item has just been revealed! Make sure you catch it while it’s lit, nobody likes a dim flame. Follow the link to the sales page...
2 x 1.2m stainless steel flue (125mm or 150mm), 1 x 1.2m galvanised insulated end cap flue, 1x 1.2m galvanised insulated flue, 1x stainless steel cyclone cowl.