It is increasingly recognised that asthma is not a single disease but that there are many different phenotypes. Much of the work that we have previously carried out has focussed on differentiating children with difficult asthma (those whose asthma control improves with attention to the basics of asthma management such as adherence) from those with severe therapy resistant asthma (ongoing poor control despite high dose treatment and attention to the basics. Our collaborators in Basel, Switzerland have demonstrated that serial measurements of lung function (peak flow) in adults can characterise the severe asthma phenotype and its stability in adults with asthma. We plan to carry out twice daily peak flow measurement sin children with asthma using an electronic peak flow meter. We will analyse peak flow patterns in children with severe therapy resistant asthma (STRA), difficult asthma (DA) and mild to moderate asthma. We will also investigate the relationship between peak flow variations and symptoms, recorded in a daily diary and medication use, recorded by an electronic measuring device which attaches to the child's own inhaler (Smart-inhaler).