Latvia's finest

In my day job as a journalist - as opposed to the real work of tending the allotment - I received a press release the other day about a new campaign called Dig Your Dinner, which is trying to encourage people to grow their own food. That is clearly a theme close to my heart, but what really caught my attention was a mention of the Heritage Seed Library, run by Garden Organic, which aims to protect 800 endangered species.
Among the 10 they highlighted were Mrs Fortune’s Climbing French Bean, which were donated to the Seed Library by two friends who share an allotment next to each other in Bristol. One of them used to visit an elderly lady called Doris Fortune in the early 1960s and was given some beans by her. They originated from an old retired gardener who tended the Royal Family's garden at Windsor.
I'm a sucker for detail like that. Take another of their endangered seeds, the Gravedigger Pea. They got them from a Mr Thompson, a retired farmer from Warwickshire, who got them from his neighbour Mr Beal who in turn got them from his friend, a gravedigger living at Kidlington, near Oxford. A real pea with a real story, not some dubious F1 hybrid bred solely for the convenience of the big growers.
Meanwhile the people behind all this have very kindly sent me some endangered seeds (the Seed Library is not allowed to sell them because they are not on the EU Seeds Register). They are Latvian Peas - which, I must confess, I have never heard of. Does anyone know anything about them? How to grow them, what their habit is, how they taste, that sort of thing? All information gratefully received - and I will, of course, report back myself as soon I get round to growing them.