The sweet pea pods are indeed hairy and the stems do have wing-like projections running the length of them. I had a look at the the edible peas grown by the gardener on the estate I live on, and while they're not exactly alike, the plants' structures all look highly similar to my 'mangetout'. For the heck of it, I also looked at some bean plants. Given how dissimilar beans, sweet peas and edible peas are, I think it's safe to assume my plant is in that latter group. If not, I suppose Dobbies has deep pockets should I need to file a lawsuit