Land wasn't taken by force. It was done through legal means. There was a series of land acts that redistributed land under both British rule and Iater irish rule. That are too complicated for me to remember.
Maybe the poster is referencing the many Protestants who left Ireland during the war of independence and after the free state was established. This was voluntary (but I'm sure many weren't happy about it) Some of this was some feared for their safety during the civil war but there were loads and loads of factors about why these affluence, educated Protestants weren't happy in an independent & poverty stricken Ireland. You could write sn essay on it.
Interesting we still pay ground rents on a small number of properties. They don't add up to a lot but the Duke of Leinster is getting 7 euro a year or something for the national library.
So no - there aren't British people waiting for us to hand back land.