The question of marriage and the age of consent are often confused. For social stability in feudal times, marriage was often planned well in advance: the informal Hapsburg motto was, "Marry!" However, there was in general a recognition that childhood marriage was rather a betrothal and might not come to consummation at puberty: the couple tended still to have a say.
With the fall of the feudal system in the 15th Century, the age of marriage generally rose somewhat, and although there were many marriages at a younger age, permitted by law and undertaken to provide for accidents, it may have become the exception rather than the rule. For example, in Oliver Twist, Nancy has been thieving for twelve years, and started at half Oliver's age, ie five, making her age 17. Yet at the same time she's been around the block a few times, and is the mistress of the far older Bill Sykes. The precedents of the work show that the criticism of such sexual mores in 1837 was already prevalent, and although it took another forty years for such paedophilia to be recognised in Law, the parity of Dickens comments and the gist of the contemporary broadside versions of this ballad come to much the same conclusion: marriage before 17 was frowned on.