Last seen for £749 at Mattress Online on 5th November 2026
Harrison Spinks Knaresborough 3750 Pocket Ortho Single Mattress
The Harrison Spinks Knaresborough 3750 is a firm pocket spring mattress whose springs move independently, which means less motion transfer when a partner shifts in the night.
- Firm feel for back & front sleepers
- Helps keep your spine aligned
- Sizes up to Emperor
Save with the previous model
Some retailers still sell the earlier version of this mattress for less than the current model's best price.
More available sizes
Last seen for £749 at Mattress Online on 5th November 2026
Mattress details
Mattress
Harrison Spinks Knaresborough 3750 Pocket Ortho Mattress
Size
Firmness
Firm
Construction
Pocket Spring
Orthopaedic
Depth (cm)
24
Layers
2
Layer Details
Comfort fillings
Wool, cotton, hemp and soft white fibres, finished with tufted layers, give natural insulation and help regulate temperature. For you, that means a breathable, foam-free top that should feel less clammy than a dense synthetic surface.
Support system
3750 individual pocket springs sit in cloth pockets, so each spring works on its own. This gives more tailored support to each part of your body, with the firm, no-sink feel the mattress is known for.
Layer details from mattressonline.co.uk product page, October 2026.
Key benefits
- Firm support for growing sleepers: A firm pocket spring surface keeps a child's or teenager's spine in a neutral line, which means good support through years of growth rather than a saggy dip by year three.
- Fits where other beds won't: At 90cm wide, this single leaves room for a desk, wardrobe and floor space in a compact bedroom, or slots under a loft conversion's slope where wider sizes can't.
- Springs that suit shared rooms: Pocket springs are quieter than open coil under a restless sleeper, which matters when two siblings share a room and one wakes before the other.
- A guest bed that supports adults: The firm ortho build means occasional adult guests get proper support, so a spare room single here does more than a budget foam slab would.
- Cheap, easy bedding: Standard single sheets and a 135 x 200cm duvet fit, the most widely stocked and lowest-cost bedding of any UK size.
This size suits you if...
You're buying for a child or teenager and want a firm, supportive base that will last through growth spurts, or you're kitting out a spare room or study that doubles as guest space, or you're a single adult in a compact room, student flat or loft conversion where 90cm of width is what the floor plan allows.
Consider another size if...
You're an adult who wants space to spread out, or you toss and turn and keep meeting the edge. The Knaresborough 3750 is 45cm narrower than the UK double, so we'd recommend the UK double instead; allow at least 2.6m x 2.8m for it.
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FAQ's
Is the Knaresborough 3750 UK single a good mattress for a child?
Yes, with one caveat. The firm pocket spring build supports a growing spine well and won't sag quickly, and at 90 x 190cm it's the standard size for children's bed frames. Very lightweight children who sleep on their side may find it a little unyielding at the shoulder, so consider how your child sleeps first.
Will the Knaresborough 3750 UK single fit a bunk or mid sleeper frame?
The 90 x 190cm footprint matches standard UK bunk and mid sleeper frames, so width and length are fine. Raised frames often set a maximum mattress depth for safety rail clearance, and Harrison Spinks' listing should be checked against your frame's stated limit before you buy.
How much room do I need for a single Knaresborough 3750?
We suggest at least 2.1m x 2.8m of floor space. That leaves enough clearance to walk alongside the bed and open a wardrobe, which is why the UK single remains the practical choice for box rooms, lofts with sloped ceilings and children's bedrooms where the bed competes with a desk and toy storage.
Can two Knaresborough 3750 singles work in a guest room?
Yes, and it's a sensible setup if you host pairs who aren't a couple. Two UK singles give each guest their own firm surface, and because pocket springs move independently, one person shifting won't disturb the other even with the beds pushed close together. Just check your room comfortably exceeds two 90cm widths plus a walkway.
Is the single Knaresborough 3750 firm enough for an adult?
Firmness doesn't change with size, so the UK single has the same firm ortho feel as the larger sizes, and it supports adult weight well for a guest bed or a student room. The question is space rather than support: at 90cm wide it suits one person who sleeps fairly still.