In addition patients will be seen at week two for a BP reading and a 24hr urine collection, and at week four for a BP reading, 24hr urine collection and measurement of renal profile (Not fasted). Advice will be reinforced at each visit and through telephone for the duration of the study. Antihypertensive treatment will remain unchanged throughout the study apart from two caveats: If BP rises >160/100 then a further antihypertensive will be added at the attending physicians discretion; If BP drops <90/60 and/or symptomatic hypotension, antihypertensive treatment will be withdrawn at the attending physicians discretion, with further investigation as necessary.