>>280730204Tina Howard is 13 years old, with Ellie Walker being 14 years old. Lynne Leinster, who will be showing up in the next episode, is also 13 years old. Caren, Allen's younger sister and Stella Howard, Tina's older sister are both 15, I believe. Same with Felicia Fosse who should also show up later.
Both Allen and Lydia Leinster should be 17 years old, as the story starts 4 years after they attended the Royal Academy and Royal University. Most join the Royal Academy at 13 years old and go to the Royal University afterwords, and the normal time from start to graduation in each institution is 3 years. Allen and Lydia graduated from the Royal Academy in 1 year, skipping grades, and went to the Royal University and did the standard 3 years there to graduation.
On a side note, while they might show up at Episode 8 or 9 (going by the pace of the anime), Lily Leinster is older than Allen by a few years (not sure if it mentioned her age), and is Lydia's cousin. Alice Alvern, the Hero of the Empire, is ??? years old; possibly a few centuries years old. Cheryl Wainwright, the First Princess, should be 17 years old as she was Allen and Lydia's classmates in the Royal Academy and the Royal University as well, though she didn't skip grades like Allen and Lydia did, I think. As for the Leinster Maid Corps and Howard Maids girls, I don't think the LN specifically mentions their ages.