Participants will undergo consenting for the procedure and their involvement in the research study. The procedures will be conducted either under local anaesthetic/sedation or general anaesthetic depending on the clinical needs of the patient. During the procedure tubes will be passed into the left upper chamber of the heart through the groin. Through these tubes catheters will be used to create a geometry of the heart chamber. Following this, in half of the participants a basket catheter with 64 electrodes will be positioned in the upper chamber whilst conventional catheters will be used in the other half of the participants. This is to demonstrate that this mapping system can effectively be used with a variety of mapping catheters. The signals collected will then be used in the novel mapping system to identify sites as potential drivers of AF. These sites will then be targeted and the response to ablation will be recorded particularly looking at slowing and/or termination of the AF, which will support these sites identified as drivers.