 All participants will then be monitored carefully over 12 months to see how many from each group get AF again. To do this, all participants will be given a handheld heart rhythm monitor to keep until the end of the study. This device is simple to use. Participants will be asked to make a 30 second recording of their heart rhythm each day and also whenever they have symptoms. These recordings will be downloaded at review appointments arranged 6 weeks, 3 months, 6 months and 12 months after the initial ablation procedure. 