Many children present with poorly controlled asthma despite high intensity treatment including high doses of inhaled steroids. A number of these children will get better once the basics of asthma management are addressed (such as adherence, allergen avoidance, smoking cessation). The remainder will need further escalation of treatment (with attendant side effects) and more invasive, investigations. Adults with severe asthma have been found to have differences in the fluctuation patterns of peak flow compared to mild asthmatics. This study will enable us to evaluate whether the same is true in children, enabling us to improve the way we identify children with difficult asthma (DA) and severe therapy resistant asthma (STRA) and whether the difficult asthma: DA group are in fact more similar to the mild/moderate group.