M&S 1500 British Wool Pocket Spring Extra Firm Mattress im Test

The M&S 1500 British Wool Pocket Spring Extra Firm Mattress is the firmest mattress in the M&S own-label range and the only one M&S labels extra firm. It pairs individually responding pocket springs with a deep layer of British wool under a pure cotton cover, and it is sold online in all five UK sizes from £429 for a single (M&S product page).

How firm is extra firm?

We record it as 9 on our 1 to 10 scale: a flat, unyielding surface where the wool adds comfort rather than sink. That is the right feel for front sleepers, who need their hips held level, and for back sleepers who like a hard bed. M&S publishes no weight limit or depth for this model.

Firm is not automatically better for your back. In a randomised trial of 313 adults with chronic low back pain, published in The Lancet (Kovacs et al., 2003), those given medium-firm mattresses reported less pain in bed and on rising after 90 days than those given firm ones. Buy the Extra Firm because you like a hard bed, not as a back-pain remedy; the M&S 1000 British Wool is the medium-firm alternative.

Materials

Like every M&S own-label mattress it is made from a short list of materials: springs, British wool and a 100% cotton cover. It has one wool layer, where the 1500 Medium has two, so the cushioning between you and the springs is thinner.

Prices by size

Regular M&S prices at the time of writing (October 2026). The small double and the double cost the same.

Delivery and returns

Delivery is £15 to the room of your choice, with a 10-day lead time and no furniture delivery to Northern Ireland or the Orkney Islands. There is no sleep trial and no stated guarantee, and no customer reviews had been posted on the M&S site when we checked.