CT Angiography (CTA) is a novel non-invasive technique where the coronary arteries can be visualised by Computerised Tomography. In previous studies it shows a high degree of correlation with invasive angiography, with a high accuracy for the diagnosis of obstructive coronary artery disease. However, the technique is relatively new, and its full role is yet to be defined in the clinical setting of a chest pain clinic. The investigators do not at present have any information as to whether it is able to speed up the diagnosis, reduce the need for other tests, and therefore also costs.