That's a shame for your students as they could be missing out on excellent teaching.
As I said, we have huge numbers of applicants so can choose between one excellent teacher and another (and another and another...). At the risk of being very judgemental, I doubt the vast majority of excellent teachers have big, visible tattoos anyway.
I would never work in a private school so I don't have to worry about that and can hire people based on how good they are.
At the risk of going way off topic, why would you not work in a private school?
I take it from this comment, you're a head or deputy-head. Do you never let appearance get in the way of hiring someone. Skinhead, union flag tattoo on the back of their head, gold front teeth and black contact lenses... as long as they have excellent experience, qualifications and answers to your questions and an incredible demo-lesson you'd give them the job?