I'm still looking, and I've found some interesting stuff. I revised my post above to reflect some of it. This page says that the current wording of the Lord's Prayer was mandated by King Henry VIII while he was still in union with the Roman Church, based on the English version of the Bible produced by Tyndale (1525). It sounds credible, but I wish he'd cited his sources.

There have been slight changes and differences over the years - debts/trespasses, who art/which art, and on earth/in earth. Those differences are really minor - otherwise, we're using a translation that goes back almost 500 years.

-Joe Offer-