Wentworth Mercer Deluxe Wool 4000 Pocket King Size Mattress
The Wentworth Mercer Deluxe Wool 4000 Pocket Mattress is a firm pocket spring mattress with wool and soft synthetic fillings beneath a viscose cover.
- Suits back & front sleepers
- Wool helps regulate temperature
- Minimises partner disturbance
£1,049
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Wentworth Mercer Deluxe Wool 4000 Pocket Mattress
More available sizes
Mattress details
Mattress
Wentworth Mercer Deluxe Wool 4000 Pocket Mattress
Size
Firmness
Medium Firm
Construction
Pocket Spring
Wool
Depth (cm)
29
Layers
4
Layer Details
Cover
A viscose cover, a soft breathable fabric, finished to a high standard. It gives the sleeping surface a smooth, cosy feel.
Wool
A plush layer of wool fibres for a luxuriously cosy feel. Wool also naturally helps with temperature regulation, so it tends to suit warmer sleepers.
Soft White Fibres
Soft synthetic polyester fillings layered on top of the springs for extra comfort. These add a gentle cushioning between you and the firm support below.
Pocket Springs
The core is 4,000 pocket springs, made from twice tempered steel, that adapt to your shape and movements. Each spring moves independently, which means personalised support and less motion transfer across the bed.
Layer details from mattressonline.co.uk product page, September 2026.
Key benefits
- More room each: At 75cm per sleeper, the UK king gives each of you 7.5cm more than the UK double, which means fewer knocked elbows and less drifting towards the middle.
- Quieter mornings for early risers: Independent pocket springs combined with the wider surface mean whoever gets up first can leave with less chance of waking the one still asleep.
- Length for taller partners: At 200cm, or 6ft 6in, the UK king is 10cm longer than the UK double, so a partner over six foot is less likely to find their feet off the end.
- Space to change position: If pregnancy has you building a wall of pillows and turning often, the wider surface lets you rearrange without pushing into your partner's half.
- A smaller footprint than the super king: We suggest at least 2.7m x 2.9m for the UK king, a little less than the 3m x 2.9m we suggest for the UK super king.
This size suits you if...
You share the bed every night and feel cramped on a UK double, one of you gets up hours before the other and wants to do it without disturbing anyone, or one partner is tall enough that a 190cm mattress leaves their feet hanging over the edge.
Consider another size if...
Your bedroom is smaller than our suggested 2.7m x 2.9m minimum. We'd recommend the UK double instead, which needs at least 2.6m x 2.8m.
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FAQ's
Is the Wentworth Mercer Deluxe Wool 4000 king size big enough for two people?
For most couples, yes. The UK king gives you 75cm each, which is 7.5cm more per person than the UK double. If you want more room than that, the UK super king gives 90cm each. That is 15cm more per person, but the UK super king also needs a larger bedroom.
Will I feel my partner move on a king size pocket spring mattress?
Probably less than on a smaller bed. The springs in this mattress move independently, so a movement on one side spreads less across the surface. In the UK king, each of you also has 75cm of your own. That leaves a little more space between you than the UK double does.
Is a UK king mattress long enough for someone over 6ft?
The UK king is 200cm long, which is 6ft 6in, and 10cm longer than the UK double. That extra length is often the real reason taller couples choose the UK king. The UK super king is the same length, so sizing up to the UK super king gives you more width but no more length.
Should I get the Deluxe Wool 4000 in a UK king or UK super king?
Choose the UK super king if width matters most and you have the room. It is 30cm wider and gives 90cm each, but we suggest at least 3m x 2.9m for it. The UK king needs at least 2.7m x 2.9m and still gives 75cm each, which suits most couples.
Will a UK king fit in a new build master bedroom?
It can, but measure after the wardrobes and drawers are in, because they take up more floor space than an empty room suggests. We suggest at least 2.7m x 2.9m for the UK king. Around 3.2m x 3.2m feels comfortable, with space to walk round both sides of the bed.