My friend just got a 15 hours per week job, term time only, she cleans from 9.30 - 12.30 in a boarding school. While the children are in lessons, she does all the boarding areas.
I also know a TA who works 15 hours a week, she does 3 days 9 - 3 (or there about) with an hour for lunch. It is term time only.
I know a guy who runs a forest school and only works mornings. He works in 3 schools and one pre-school setting, 9 - 12 works out at 15 hours a week. He does work out of term time, running a holiday club, but that is because he wants to, and its a self employed thing on the side.
I also know a whole team in a Pre-School who only work 9.15 - 12.15 Monday to Friday term time only (15 hours a week).
Lastly, I know a tutor who works mostly evenings, with a couple of sessions in the day for home school people and that's term time only and she said she does about 15 hours a week. She gets to choose her hours because she is self employed.
So I seem to know quite a few people who work those hours, but all of them either work in education, or in an education setting.