Inclusion criteria:  Age 18 to 80 (inclusive)  Patients with symptomatic advanced persistent AF as defined based on a combination of temporal behaviour of AF, AND the presence of co-morbid conditions:  History of continuous AF of 3 months or greater, with early recurrence (within 1 month) after electrical and/or chemical cardioversion, AND the presence of either:  Chadsvasc score >2 in men and >3 in women, OR Chadsvasc score >1 in men and >2 in women, AND one or more of the following: age 75 years or greater, severe left atrial enlargement on echocardiography (one or more of the following (indexed to body surface area): anteroposterior diameter >3.0cm/m2, 2D area >40cm2/m2 or volume >40ml/m2), chronic kidney disease with eGFR <45ml/min/1.73m2, tachy-brady syndrome with a pacemaker in situ for documented sinus node disease  Exclusion Criteria  Any previous catheter (or surgical) ablation for AF (previous ablation for atrial flutter or focal atrial tachycardias are allowable) An indwelling atrial septal defect occluder device or anatomical structure that pre-vents free access to the left atrium Severe left ventricular systolic dysfunction (ejection fraction less than 35%) Recent stroke/transient ischaemic attack within 3 months Inability, unwillingness or absolute contraindication to taking an oral anticoagulant medication Severe kidney function impairment (eGFR less than 30ml/min/1.73m2) Morbid obesity with a body mass index ≥40 Extreme frailty (a score of 7,8 or 9 on the Rockwood Clinical Frailty Scale) Severe valvular heart disease of any kind as assessed by the investigator, with or without a prosthetic valve in place Pregnancy