You are conducting an annual check on an 81-year-old male in a GP surgery. This patient is fit and well and has no relevant past medical history of note. On examination, you note that his blood pressure reads at a value of 150/85. You follow the NICE guidelines and conduct a second reading in the other arm which reads at a value of 151/87. You have confirmed the diagnosis of stage 1 hypertension via AMBP monitoring and you can now discuss starting medication with this patient. The patient agrees to starting medication. What is the most appropriate first line drug to start here?