I was thinking Big Belly Ben could be one of the descendant of Lucamore the Lusty. Several of his wives and children were banished to the Stormlands. Almost all of the Strongs were giants of men and physically strong as their name suggests. Ben is supposed to be a pastiche of Little John and Friar Tuck. A possible grave of Little John was found in Hathersgate and the skeleton indicated a man between seven and eight feet tall. I suspect Big Belly Ben was a mountainous man of both height and girth and that would work for being a Strong.