Most children will be started in the study through their general practitioner clinic. It will take one year to enroll all 900 children. Once enrolled the children will be followed-up in hospital centres. Much of the funding will be required to recruit and follow-up the children, train everyone to the same standard and develop and administer the questionnaires and health economic assessments. Asthma care is an expensive. The investigators will look at the costs and assess which treatment offers most benefit. The team has experience and ability in this field and will ensure the results are well publicised. Any child can withdraw from the study at any time.