I don't know about runner beans, but my TB likes bananas and pineapples (I have to walk through their yard to reach compost heap in field and get mugged). Funnily enough sturdy Welshie doesn't like exotic stuff like that although he is a bit like a locust in that he can strip a field bare in seconds!
Our sturdy welshie didn't like bananas until he saw dhorse and the shetland tucking in and all of a sudden he wants them too. Odd that! Haven't tried pineapple but they all love nectarines (I take the stone out) and dshetland does sweet little whickers and holds up her hoof for more.