M&S 3500 British Wool Pocket Spring Firm Mattress im Test

The M&S 3500 British Wool Pocket Spring Firm Mattress is the firm model at the top of the M&S flat-topped range: 3,500 pocket springs by M&S’s count, two deep layers of British wool and a pure cotton cover. It is sold online in Single, Double, King and Super king, from £649 for a single (M&S product page).

What the extra money buys

Compared with the 1500 Luxury Firm and the 1500 Extra Firm, the 3500 Firm adds a second layer of wool and a higher spring count. M&S does not state which size the count refers to or the spring gauge, so the number tells you the tier within the M&S range rather than how it compares with another maker’s 3,500. M&S rates it firm, and we record 8 out of 10.

It suits back and front sleepers who want a firm, level surface with more cushioning on top than the 1500 firm models give. Customers on the M&S site rated it 4.7 out of 5 from three reviews when we checked in October 2026.

Is it worth the price?

The Double costs £749, above what most UK buyers spend on a new bed. The National Bed Federation’s consumer survey found that 46% of recent buyers spent up to £399 and three quarters spent under £800. If budget is the limit, the 1500 Extra Firm gives a firmer M&S feel for less, with one wool layer instead of two.

Prices by size

No small double is listed. Prices are M&S’s regular prices at the time of writing (October 2026).

Delivery and terms

Delivery costs £15 to the room of your choice, with a 10-day lead time. M&S lists no sleep trial and no guarantee period, and mattresses come back only under your statutory rights.