I tried the Sealy PostureTech Alderney Mattress in a Dreams store, and I came away understanding exactly why owners love it and exactly why I wouldn't buy it. It's firm, it has a soft foam top, and it doesn't cost much for a Sealy. But the springs are Sealy's own PostureTech, a variation on open coil rather than pocket springs, and for this money you can have a firm pocket-sprung mattress that keeps each sleeper's side of the bed to itself.
How I tested it, and what I found
I tried the Alderney on the shop floor at Dreams in March 2025. I'm a side sleeper and weigh about 61kg, which makes me lighter than the person this mattress is built for, so I lay on it the way I sleep and then fidgeted about the way I do at two in the morning.
On my side it was firmer than my body needs. My hip and shoulder met pushback instead of sinking in, the sort of bed where you start rearranging the pillow to make up for it. The memory foam on top takes the edge off, enough that it doesn't feel like a board, but it doesn't cradle a light side sleeper. The pleasant surprise was the edge. Sealy's EdgeGuard border stayed firm right out to the side, so the whole width is usable when you roll over, and you don't get that slightly seasick feeling near the edge of a cheap spring unit.
The shop floor matched the spec. This is a bed for back and front sleepers who want firm, and I'm not one of them.
Firm springs, a soft lid
Underneath is a unit of twice-tempered PostureTech springs inside that EdgeGuard border. On top sits a layer Sealy calls MemorySense, which is memory foam with a trademark, then a layer of responsive foam, all under a quilted knitted cover. It's 25cm deep, firm, single-sided and made in the UK for Dreams.
Twice-tempered sounds grand. It means the wire has been heat-treated so it holds its shape longer, which is good, and which most decent spring units do anyway. The detail that decides it for me is that PostureTech springs work as one connected unit, so when a partner turns over, you feel it.
Lovely for one, less so for two
If you sleep alone, on your back or front, and like a hard bed with a little give on top, it does the job. Owners use the same words again and again: firm but not too firm, with a soft topping. One found it a touch firmer than expected on arrival and was hoping it would ease, which is the label doing what it says. Couples who already wake each other up should avoid it; a connected spring unit won't help that marriage.
You can't flip it, so rotate it head to foot every week for the first three months, then monthly. It isn't made for an adjustable base either.
What to buy instead
Buy a firm pocket-sprung mattress at the same price, and if you can find one you can turn, take that. Same firm feel, a partner who stays on their own side, and a mattress that wears evenly. My objection to the Alderney was never how it sleeps. It's what else the money could have bought you.
