Joybell is right - a lot of Victorian Parlour Ballads that people have come to think of as jolly romps are really serious songs, and they benefit from being sung that way.

That applies for quite a number of other songs that always tend to be given the jolly singalong approach. For example, "The Titanic", which can send a shiver up your spine. For that matter so can "All for me Grog" - I once heard Tim Laycock sing a slow straight version of that, which had a quite extraordinary impact.