Marriage at 17?

[LizzieL]

The whole point of the calling of Banns the parents or anyone else to raise an objection.

That works if the underage bride or groom is still residing with their parents prior to marriage. But if they go to another parish to be  married the parents may be completely unaware of their intentions. They only need to be away from the parental home long enough to leave a suitcase of clothes in a distant parish and contact the vicar there, then go back three weeks later for the actual marriage ceremony. Once the railways were invented you could get quite some distance in a few hours. 

[GrahamSimons]

No, the parents consent is not published. The whole point of the calling of Banns the parents or anyone else to raise an objection.

Although it isn't required to be recorded, some vicars helpfully state that consent was given by the bride or groom's father or mother and name them. Sometimes if consent is given by the mother, it might be recorded that the father has died. I've only seen this on pre 1837 records, some of the pre-printed marriage record forms had a "with consent of" section.

We also see in Bishop of London's marruage licences from time to time "by consent of friends" which suggests being away from their original parish, and also "by consent of guardian" when both parents have died; the guardian usually named, the friends not named.