The theme for this year's World Mental Health Day, which takes place tomorrow, is "Mental Health in an Unequal World' and is meant to highlight the perennial problem of inequity of mental health services around the world: The deficiency in the quality of care provided to people with mental health issues; the paucity of investment in mental health; and the continuing and intractable stigmatisation of and discrimination against the mentally ill.

But there is an inequality which is of a lesser scale that resides within the microcosm of the relationship between a patient and a doctor and is not so obvious - perhaps because it is an inevitable and inherent part of that relationship.