In all the yappitry about marriage and "tradition" recently, in the back of my mind I had that the tradition in Scotland was incredibly free until very recent times. I found a good reference to the principles today:

A `regular' marriage was one for which the banns had been proclaimed and which was then celebrated by a minister in the parish church. An `irregular' marriage, under Scottish law, could be of three kinds: per verba de praesenti (a mutual agreement to marry at that moment), per verba de futuro subsequente copula (a promise to marry in the future followed by sexual intercourse), and `habit and repute' (cohabiting in such a way as to imply that mutual consent to a marriage had been given). It was only the forms of constituting it that were irregular. The marriage itself was in every way as binding as a regular marriage, and with the same restrictions: both parties must be free to marry, they could not be within the forbidden degrees of kinship and they had to be over the age limit (twelve for women and fourteen for men). Neither witnesses nor parental consent were necessary.

All very none of yer friggin' business. The church, professionals and, indeed, the state are quite the johnny-come-latelies to the issue of marriage as well as most community ceremonies such as funerals. So why someone suggests we need to move back to Christian traditions, those are some of mine - I quite like the principle of "a promise to marry in the future followed by sexual intercourse".