Snails are very popular here in French Catalonia and when the weather is damp you often see people poking around stone walls and hedgerows gathering them. They are not the big fat Roman/Burgundian snails but just the ordinary garden snail. A common way to cook them here (after starving and rinsing) is also in tomato sauce. They're also the main feature in communal village snail barbeques, the 'cargolade', that tend to occur in late Summer/Autumn when the weather is damper and the snails are still plump on summer plants. Personally while I do like Bourgundian snails with loads of garlic butter, I find the grilled ones to have rather a strong and none too pleasant taste. I have prepared and eaten snails from my own garden but I do them with garlic butter, or just add them to a paella.
As I said I have encountered garden snails in old regional English dishes from Sussex and Somerset, where they are usually known as 'wallfish'. And there used to be (some 20 years ago now) a restaurant in Wells, Somerset, that served locally caught Mendip snails. The big edible/Roman/Bourgundian snail does occur in England but the only place that I've ever found them in sufficient numbers for a meal was at Box Hill in Surrey.
I think all species of snail in Europe are edible and they are as you say, ID, full of protein, if not that much in an individual snail. Hence I guess they have always served as poor people's food and in times of famine. I remember in Louis de Bernier's "Capatain Correlli's Mandoline" the Kefalonian islanders were forced to live mostly on snails when the island was occupied and all the fishing boats commandeered by the Germans.
It was just two years ago, when my partner died and all the bank accounts were frozen, that I too was forced to eek out my rations by foraging for free wild food, hence my collecting snails from the garden, along with nettles, dandelions, wild mushrooms, loads of chestnuts etc. And rambling off the subject a bit further, amongst all the current doom-mongering about economic meltdown, I at least can take some comfort from William Cobbett's "Rural Rides", in that he observed that those people in Surrey, Sussex, Hampshire, Wiltshire who lived in mixed agricultural districts with plenty of common woodlands, were consistently better able to feed themselves than those who lived in areas entirely given over to crops or arable pasture. So again, in the agricutural depression after the end of the Napoleonic wars, I guess anyone in the countryside that could, was readily foraging for wild greens, berries, mushrooms, small birds, hedgehogs, fish, snails and indeed probably frogs too.