Anxiety disorders are one of the most common classes of mental health disorders. The lifetime prevalence of at least one anxiety disorder is 25 to 30 per cent (Clark & Beck, 2010). Given that anxiety disorders are so common, they are seen frequently in primary care settings (Demertzis & Craske, 2006), where lifetime prevalence rates in this setting have been reported at 12 to 30 per cent (Sartorius et al., 1996; Weiller et al., 1998).