Ask a bed shop for something firm with wool on top and you're making one of the oldest requests on the shop floor: a mattress that keeps your spine level all night, with something soft and natural between you and the springs. The Wentworth Mercer Deluxe Wool 4000 is Mattress Online's own answer to it. Wentworth Mercer is the shop's house brand, and this is the Firm rung of its Deluxe line, one step up the range from the Medium Deluxe Wool 3000 and one below the softer, cotton-filled Deluxe Naturals 5000. Lie down and the first thing you meet is wool and fibre, cushioned and dry, then the springs meet you almost at once and keep your hips up level with your shoulders. For a firm wool bed in the Wentworth Mercer range, it's the one I'd send you to.
The step from the 3000 is small and specific: a Firm grade instead of Medium, and 1,000 more springs in the same single layer, with the same wool, the same polyester fibre and the same 29cm depth. What the 3000 has over it is the thing I care about most: it's sold as a mattress you turn over, no question, and whether this one turns is less clear-cut. So most people shopping Wentworth Mercer should buy the 3000, and the 4000 belongs to the sleeper who already knows Firm is how they sleep best.
How firm is the Deluxe Wool 4000?
Firm, with a cushioned top and nothing soft underneath it. Under the cover sits one layer of wool, then two layers of polyester fibre, then the springs, and the whole top is tufted, tied through so the fillings stay put. That makes a flat, close surface. On your back the wool gives a little and then the bed pushes back evenly from your shoulders to your heels, which is what people mean when they ask a shop for firm. Front sleepers get the same flat platform, so your hips don't drop and your lower back doesn't bow. Nothing in those layers is slow to recover, so the springs answer straight away and the bed feels lively when you turn over.
It started out graded Medium to Firm and has been sold as Firm since, with the same springs and the same depth. I read that as a bed near the gentle end of Firm. If you're picturing the paving slab the showroom bloke steers people towards, this is kinder than that.
Right for back and front sleepers, too firm for light side sleepers
This one sorts people quickly, and the order I'd sort anyone in is weight, then position. Average-weight and heavier back and front sleepers are its fit. Over about eighteen stone you want firm, and this is firm on a full layer of full-height springs. My partner sleeps on their back or front rather than their side, which is exactly the sleeper a Firm grade is made for. I sleep on my side, and I'd want more give at the shoulder than one layer of wool over fibre allows.
Side sleepers under about nine stone should walk straight past this one. Your shoulder and hip won't sink far enough into a firm bed with this little cushioning, and you'll wake with both of them aching. And don't buy it because firm sounds good for your back. Firmer isn't better for backs, whatever you've been told, and medium-firm is where I'd start almost everyone. Buy it because you already sleep well on firm.
One full layer of springs, 1,000 more than the 3000
All 4,000 are full-height pocket springs in one layer, with no thin mini springs padding out the number, and I give it full credit for that. Plenty of beds wearing bigger figures are mostly mini springs underneath. A full layer of around 3,000 is already a sensible count to my mind, though, and past that, more springs in the same space just means smaller springs closer together. You won't feel the extra 1,000 over the 3000. You'll feel the grade. If you're choosing between the two, choose on Firm against Medium and let the count go.
The springs are sewn into separate pockets and move independently, so a partner rolling over sends far less through the bed than an open coil would. Pocket springs cut movement down a lot. They don't make it vanish, so you'll still notice a very restless partner now and then.
A hard edge, stitched by hand
The edge is where this bed shows what it's made of. A thick rod wire runs round the border to keep the springs in place, the springs run right out to the sides, and two rows of hand side-stitching tie the border into the spring unit. You can perch on the edge and sleep right out to it without feeling you're about to slide off. On a double shared by two people, that's the difference between using the whole width and fighting over the middle. Sit on it in the first week and check it for yourself, and ring the shop early if it gives more than you expected.
Handmade on its own has never sold me a bed, and machines make good mattresses too. Stitching that binds the border to the springs is different. It's a piece of construction with a job to do, and here it does it.
An owner it didn't suit, and what that tells you
Happy owners are generous about it: one called it probably the comfiest they'd ever had, with great support and plenty of comfort, and said it looks and feels like a "high end hotel mattress". Hotel feel, translated, means new, firm-ish and tightly made, and that's a fair description of this build. If you're small, read this unhappy owner closely. She describes herself as quite small, found it very uncomfortable, said it started to "bag in the middle" within a couple of nights and asked to exchange it for something much harder.
A dip that early is the worst thing a new mattress can do in my book, and if you see one, ring Mattress Online the same day. The first fortnight on any mattress lies to you, though. Wool and fibre bed down under a body in the first weeks and need rotating to recover, and a lighter body on a firm bed feels that settling more than most. A topper wouldn't have rescued it either, because a topper fixes too firm and never fixes a dip. If properly hard is what you want, take her at her word: this is a cushioned Firm, and rock hard sits further up the scale.
Ask whether it turns, and rotate it regardless
Settle one thing before you pay. Mattress Online's page calls the Deluxe Wool 4000 double-sided and single-sided at once, while the photos show tape handles on the side. Ring them, ask whether it turns, and get the answer in writing. I'd much rather it turned, because a mattress with wool on both faces that you flip lasts longer, and no-turn is a saving the trade dressed up as a feature. Whatever they tell you, rotate it head to foot from the start, because natural fillings need regular time off from your weight to recover.
The practical side is easy. It's 29cm (about 11.4 inches) deep, just short of the 30cm where I start warning people about fitted sheets, so ordinary deep sheets fit. The 100-Night Comfort Trial is an exchange, not a refund, and it only counts if you buy Mattress Online's own protector with the mattress, so put one in the basket before you check out.
Is it worth the money?
It's fine for the money, and that's a compliment from me. With a house brand like Wentworth Mercer your money goes on the build rather than a famous name on the label, and the build here is honest: wool, full-height springs, a rod edge and proper stitching. The Natural Pocket 2000 costs less and gives you the same Firm grade and a rod edge, sold plainly as double-sided, but with cotton and polyester fillings and half the springs. What the extra buys on the 4000 is the wool and the fuller spring layer. If wool is why you came, pay it. If it isn't, save it.
Be clear-eyed about the wool, too: there's one layer of it over two layers of polyester fibre, so most of what's between you and the springs is synthetic. Wool sleeps cooler and lasts better than fibre, and I'll always take it, even as the smaller share. Call it a wool-topped bed and you'll have it right.
What to buy instead
For most people, the Deluxe Wool 3000: the same wool, a single full layer of 3,000 springs, a Medium grade far more people sleep well on, and sold as a mattress you turn over. If you want firm and you want no doubt about turning, the Millbrook Wool Luxury Ortho 2000 at the same shop is double-sided with turning handles and puts wool and cotton over its springs. Light side sleepers should go softer, to the Deluxe Naturals 5000. And if you're a back or front sleeper who knows firm suits you and wants wool on top, stay right here: the Deluxe Wool 4000 is the Firm wool pick of the range.
