Simpsons Premium is a UK maker, and the reason to look here is the protein list. Simpsons have recently added a wet range that runs to kangaroo, ostrich, wild boar, venison and rabbit. That's unusual anywhere, and useful if your dog reacts to the usual meats.With 38% crude protein for the 80/20 range and c.25% for standard recipes.
Three dry ranges
Standard recipes use brown rice: chicken or lamb, with puppy and senior versions. These are grain-inclusive, and perfectly good everyday food for a dog with no particular problem.
Sensitive recipes swap the rice for potato and come in salmon, chicken, lamb or duck. Grain-free, and the range to look at if you're working out what your dog reacts to.
80/20 is the high-meat tier, and the dearest.
Unusual proteins in the wet range
Kangaroo and ostrich are what vets and behaviourists tend to suggest when a dog has already reacted to chicken, beef, lamb and fish. The point isn't that they're exotic, it's that most dogs have never eaten them, so there's nothing for an immune system to have learned to object to.
If you're going down that road, do it properly. A novel protein only tells you anything if it's the only protein your dog gets, treats and chews included. Talk to your vet before you start, because a proper elimination diet takes weeks and needs planning.
Who Simpsons suits
Dogs with food sensitivities that haven't been solved by the usual grain-free routes. It's also a good option if you'd rather buy from a UK maker.
The wet cans work well as a topper on a dry food too, if you want to make dinner more interesting without changing the whole diet.
Who it isn't for
Anyone who wants to try before they commit. Most of this range comes in large bags only, so it's a substantial outlay to find out whether your dog likes it. If that's a concern, Carnilove covers similar ground on novel proteins in smaller bags.
And if your dog is well on an ordinary food, this is a lot of money for no benefit. Novel proteins solve a specific problem. They aren't an upgrade for a healthy dog.