Methods: We will study 240 children and adults in 12 centres. We have matching placebo and Flixotide metered dose inhalers to be used through a Volumatic, so any subjects currently on Pulmicort or Becotide will switch to Flixotide 2 months during the run-in phase, and all subjects will use their ICS through a spacer device. Patients will be randomised to continue on ICS or take placebo for 6 months, in a double-blind fashion. Primary outcome is time to 1st exacerbation; secondary ones are decline in lung function, new courses of antibiotics and rescue bronchodilator usage.