Well, I've just had a look at what was available in John Lewis:
1) Brushed cotton flannel sheet. This seems awfully thin and flat for a quilt?!
2) Polyester, no labels, seems not very dense. I think this is what I used for Gran's quilt. It's OK.
3) Natural cotton, needled, it's this:
https://www.johnlewis.com/cowens-nee...white/p3399982. Very lovely and fluffy and light, and not at all what I thought cotton wadding would be like, so that's a useful experience! But this one is perhaps a bit fragile. The lady behind the till said she uses it for all her quilting projects but you do have to treat it kindly. I think it's a "high loft" version, and if I get something denser it will be tougher but harder to sew. I can't find any info on what loft they'd call it, recommended quilting distance etc. - it seems Cowens specialise in "carriage and coffin trimmings" and kits for soaking up spills of hazardous substances, rather than crafting!
The polycotton was out of stock, so I don't know what that, or denser cotton, would be like.
I was also firmly told by the John Lewis staff that for a wedding present I should avoid polyester because it has a much lower range of comfortable temperatures (something I can agree with from my polyester jumpers which I can only wear when it is seriously freezing), and so was more likely to result in disputes over whether it was warm enough to need it on a bed! I hadn't thought of that parameter
