Not me, but I have several colleagues whose subject specialism is not maths, but either because of a shortage of qualified maths teachers, or for whatever reason, they are teaching numeracy or maths up to GCSE foundation level.
Don't get me wrong, I am not a snob and there are plenty of effective teachers who are not officially "qualified". On the other hand, I have seen several examples of poor understanding of maths from the teacher, leading to giving wrong information to the class.
What is there to do? Nobody wants to teach maths anymore.