Are you feeling symptomatic with the lower heart rate? Dizziness, blurred vision? Do you feel lightheaded when you stand up? If you have none of that, it would be improper to treat the heart rate. It could be your body compensating for your borderline blood pressure issue, it could also be just your natural set point. If you are a bit of a hypochondriac your B/P could be high due to that. It's also called white coat syndrome. Certain medications can also alter your heart rate. If you have been put on a Beta blocker for example. Those would be drugs that in the USA would have a name that ends in an OL, such as Metoprolol, or Atenolol. Not sure if the Aussie names are the same or not.