Trying to work out if my friend is Orthodox Halachically Jewish

I couldn’t find a clear answer on the flowchart, so I’m asking here.

A friend of mine recently found out that he has Jewish ancestry. He was never raised Jewish, his parents never engaged in any religion besides Anglican Christianity, and he had never considered considering himself Jewish.

He found out, however, that his ancestor (on his fully matrilineal line) was a Jewish woman who hid her Jewish heritage to escape persecution (likely in the late 1800s) and married a Christian man. He asked me if he would “technically” be considered Jewish (for interest’s sake more than anything) and I figured I’d ask here.

Even though all of his ancestor’s descendants have practiced Christianity, and she stopped publicly practicing Judaism by the time she had children, would her matrilineal descendants not still be considered Jewish by Orthodox Halacha? Is my friend Halachically Jewish, even if not functionally?