This study evaluates the validity of claims that Working Memory (WM) training is an effective and legitimate school-based maths intervention. By analysing the current developments in WM in the fields of neurology and cognitive psychology, this study seeks to analyse their relevance to the classroom. This study analyses memory profiles of children and maths performance previous to, and after a 3 week school-based, teacher led, intervention programme. Results indicate that although WM improved, it also improved for the control group, who did not undergo training. No significant far-transfer to maths results were demonstrated during the study.