where to buy 100% feather duvets?!

[Isabelll]

I need a duvet pretty soon, looking to invest in a really nice one and want a mostly (85% and up I think) feather duvet - I like the weight of them. Cannot for the life of me find one. ALL of them are feather and down and reviews say they're lightweight. I don't want a light one, I find light duvets annoying. 10.5 tog and king sized too! Can anyone suggest companies that do feather duvets which have a bit of weight to them? Not specifically a weighted blanket, just a moderately heavy duvet.
Thanks!!