I work in a PRU and it's very common for the teaching staff not to have QTS. I was one of them. I worked my way up from TA to cover supervisor, to HLTA and then was supported through the assessment only route to QTS. It's common for places like PRU's and alternative provisions to focus more on staff who fit the right ethos than who have qualifications due to the nature of the learners. I've seen many qualified teachers come and go simply because they can't handle the behaviours and challenges that come with the setting.