Why not consider this recipe?
Here in the U.S. we don't call them 'runner beans' but our are similar, at least in pictures. We do this all the time during season:
Runner beans in olive oil
Ingredients
1/4 cup olive oil (I don't use EVOO for this, use a milder variety)
1 to 2 cups chicken or vegetable stock
1 to 2 pounds of beans prepared (cleaned and ends cut off)
1 large chopped onion (more for 2 pounds of beans)
1 whole chopped garlic (more for 2 pounds of beans)
2 large peeled and chopped tomatoes
salt and black pepper to taste
pinch of sugar
Method
Fry the onions in a little olive oil until just soft. Add the garlic and fry a little more.
Add the tomatoes and cook until they are soft and then add the beans, salt and pepper. Mix well and fry for a further 5 minutes.
Now add enough of the stock to somewhat cover the beans and simmer until the liquid has evaporated and the beans are tender.
Serve hot or cold