Well, this was a dream last night, so here goes...
Queen Elizabeth I and King Thomas I
Now, the only other detail in the dream seemed to be that the reign was a joint one and that it ended in the 1590s.
Could Elizabeth marry before ascending the throne? I don't see any particular reason why not, and IIRC Thomas Seymour and her were contemporaries, well I think he is a few years older.
If not Seymour, is there another Thomas around?
Best Regards
Grey Wolf