There is a good recording of "Dives and Lazarus" by the young Tradition, which you can compare with versions of Gilderoy so see the similarity of the tunes.

My personal favourite 'stretching' of tunes is Greensleeves, from the version everyone knows to the morris "Green Sleeves and Yellow Lace" etc. In fact, a group called the Monkseaton Morris Men used to do a set of about 20 minutes which was all variations of Greensleeves: sung, English Country Dance, Morris, SOlo Jig and probably several others.