The regulation accords that the material used should be fire retardant but it was not in case of you. Here are the guidelines on safety of furnishings. https://www.newcastle.gov.uk/business/trading-standards/product-safety/guidance-on-the-safety-of-furniture-and-furnishings
Next time when you buy try to go for fire retardant material.
Please check furniture and furnishings fire safety regulations here https://www.newcastle.gov.uk/business/trading-standards/product-safety/guidance-on-the-safety-of-furniture-and-furnishings
Since cotton is not fire retardant so you need to take advice from some official authority in this case. However, in both the cases labels have to be there.