Last year I purchased some seed from Cyprus. all germinated and I grew them up sticks just like runner beans. I had a fantastic crop of enormous butter beans. They have been used in soups and mainly chorizo and Bean stew. I would recommend growing them to all members. Real seed do them I think.
Can confirm your comments. They are vigorous ! Bees find them attractive too.
I tried the Greek Gigantes last summer, the nearest I have ever got to butter beans, just using the last ones up but plenty of seed saved for this year. They sell them as runners but I found them to tough and stringy for use as green beans. Certainly a good yield.
I tried some similar Spanish beans - they produced enormous plants but very little in the way of beans. Shame as they were lovely in a stew.
I've tried Gigantes in the past but without much success... might try them again..