In the end I answered my own question and went for the non-woven multi-layer one https://www.ebay.co.uk/itm/263249270027

Quality product, fits well (including with the luggage rack in place), good value (around half my original budget), so I'm happy with my purchase.

I suggest cutting-off the annoying and unnecessary dangly retaining straps. These covers are BIG and hard to photograph -- the fit is more duvet-cover than pantyhose, so growing an extra pair of arms is recommended. And I'm planning to attach a sew-on Morgan logo to the end I start with (in my case the rear), to avoid chasing the edges to find the starting point.

[Linked Image]

Peter
2009 3-litre Roadster "Ivor", royal ivory / green