Mitochondrial DNA is inherited through the mother's line. We all have mitochondria and we all have mitochondrial DNA that traces back through maternal bloodlines. A roman soldier could have had a mother or other female antecedant who was Romani.
You can't get mitochondrial DNA from your father. It's not possible.
Even if a Roman soldier had a gypsy mother, none of his children would have her mitochondrial DNA.
My sons have my mitochondrial DNA but it stops there. Their children will get their mitochondrial DNA from their mothers.
I went back and reread my #8 post. There, I clearly stated that Mitochondrial DNA is inherited through a female. I proposed that Gypsy traders and family might have been in England earlier than previously believed.
What I said about the Romans, who have nothing to do with the Roma (Gypsy) people, was merely to point out earlier non Anglo Saxon influxes of Eurasian people. I know that the MDNA would not be from the men, but what was Roman policy on wives and campfollowers being transported with their troops? Remember, someone had to do the cooking and sewing.