Been searching for a Goose feather & down duvet for a few weeks and came across this one from an ebay shop. These duvets are about a third (sometimes even a quarter!) of the price I've seen in the shops and are good 100% cotton covered 85% feather and 15% down ones. Mine has arrived and I can confirm it's lovely quality and snuggly and warm! They do a duck feather & down one too which is even cheaper if you prefer duck. All sizes were available.
13.5 Tog Duvet (Autumn/Winter thickness)