So just arrived in DXB from LHR on QF in J. Had planned to sleep onboard, so ate in the BA FLounge at T3 and put the seat back right after takeoff.
The nifty little mattress addition to QF's business class offering is a real treat. It's only a thin little thing, but it manages to cover over the usual lumps and bumps on a flat bed seat to make the surface much, much more comfortable.
It slides over the top of the seat (including headrest) and didn't move at all that I noticed.
If only BA could add something similar to CW. It doesn't require a 'turndown' service as it's just so simple you can do it yourself, but would make a huge difference I think!
The QF seat is a similar shape to CW, so I reckon it could work in much the same way?
(That, QF's J class pyjamas and new EK-inspired chauffeur service at LHR and DXB made for a very pleasant experience... and with a great fare too.)