The term 'where's that to' is alocal dialect which sounds either quaint or annoying to someone not from that area. For you it seems to be just one more annoying trait of this particular colleague. My gripe is with teachers using to wrong tense for the verb 'to sit'. For example, "He was sat on that chair", "You were sat with Josh", "They were sat in the front row". A teacher who talks in this way to pupils goes down in my estimation. I just can't be stood for it.