I don't do much research in England and don't have access to ancestry.com's English records, etc. However, I'm working in England between 1550 and 1680 and running into some date issues in some of the records I'm finding.
For example, what is date 20 Car. I, or 1 Jac. I? I assume it has something to do with Cromwell, but not sure where to look. Does it refer to the reigns of Charles or James? How do I get a date that is clear to modern readers, like me?