Some months ago I bought a cushion from Homebase's. Subsequently I unknowingly dropped some glowing - I assume - cigarette ash on it. Within 10 minutes the house was full of smoke. I found that this cushion cover was burning progressively and rapidly . Definitely non fire treated.
Comment please.

The regulatory requirement for scatter cushions and seat pads is that the filling material only must satisfy the relevant ignition test and each individual item must bear a reduced information permanent label. Whilst the size of a scatter cushion is not defined in the Regulations it is commonly accepted that a scatter cushion has dimensions which are less than 60cm x 60cm x nominal product thickness.

Check out Fire safety of furniture and furnishings in the home - A Guide to the UK Regulations

Did it meet that criteria?

 

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.

The Regulations are enforced by Trading Standards check out https://www.gov.uk/find-local-trading-standards-office.