Just came across this debate. It may be a bit old now but I thought the following might be of interest.

The excellent work of reference, "Ancestral Trails. The Complete Guide to British Genealogy and Family History" by Mark Herber and published in association with the Society of Genealogists states in its section on "Marriages and Banns" that minors were people under the age of 21 and that:

"Under Hardwicke's Act, minors had to obtain their parents' or guardians' consent in order to marry but, until 1929, the law still allowed boys as young as 14 and girls as young as 12, to be legally married with that consent." (Herber, 2004, p124).

I hope that is helpful.