Happy owners, a turnable build and a low price: the Highgrove Solar Luxury Dream Mattress has the lot except the spring unit, which is an open coil, so I'd keep it to a spare room or a tight budget. Owners are very happy with it. I don't doubt them. My reservation is the open coil itself, which passes movement and tends to dip with nightly use. Avoid it as an everyday bed for two, and buy pocket springs for that.
A traditional open coil, properly upholstered
Inside is an open coil, rows of springs joined by wire, with a thick rod-edge wire round the unit. It's hand-tufted, with cotton tufts on both sides holding white fibre fillings in place, under a Belgian damask cover. It's 26cm deep, rated firm and double-sided; Highgrove says to flip and rotate it.
It's a decently built traditional mattress. The turnable design is the best thing about it. The open coil is the thing I'd change: you'll notice a partner's turn if you're a light sleeper, as I am. Flip and rotate it every few months, as Highgrove suggests.
Happy owners, mostly in spare rooms
The reviews are very positive: owners call it firm, thick and good value, while some bought it for a guest room, which is exactly the job I'd give it. There are no complaints worth worrying about.
What to buy instead
For everyday use, the Highgrove Solar Pocket 1000 keeps the double-sided, firm build and swaps the open coil for pocket springs. For a guest room, the Luxury Dream is a sound choice, and visitors who like a firm bed will be happy on it.