Mathematics teacher educators in the University of Limerick became aware of a lack of conceptual understanding of key mathematics concepts of prospective secondary mathematics teachers through observation on teaching placement and in pedagogy lectures. A pilot study to enhance the conceptual understanding of prospective teachers was carried out with one undergraduate class in 2009/10 and a longer more in-depth programme was offered to all prospective mathematics teachers in the academic year 2011/12. The intervention was designed to get prospective mathematics teachers "thinking" about mathematics topics they have so far taken for granted and hence better prepare them for classroom practice. This retrospective study divulges a number of observations which emerged, the main one being how rote learning and an emphasis on procedural skills at the expense of conceptual understanding results in a cycle of ineffective teaching which is difficult to break.