The Barnet pair, who both attend JCOSS, were invited to the event by virtue of being one of the top 32 players in their age group in England.
And although they were unable to progress through the group stage into the main draw, they both reached the final of the consolation event, with Millie taking gold and Louis silver.
Millie defeated Sunderland’s Charlotte Weatherby 3-1 (11-4, 11-7, 5-11, 11-6) in her final, reversing the scoreline from the group stage earlier in the day.
Millie, aged 12, said: “I’m so happy. I didn’t expect it but I tried my best and kept fighting. Being at the Nationals is quite overwhelming and there are a lot of good players, but it’s very cool as well.”
