Sometimes even the most enlightened among us can lapse into a conventional view of disability that downplays the invisible. Mental illness and covert physical disorders require a profundity of understanding and subtlety of approach that easily evades policy makers.

Pips, like the outgoing Disability Living Allowance (DLA), are meant to tackle the excess cost of independent living that disabled people otherwise have to shoulder based on a points system. The trouble is that disability assessments that rely heavily on what the applicant tells you rather than a physical examination or medical tests, in other words that is more subjective, is less likely to score highly or at all. Often the lingering, whispered suspicion is that the applicant is swinging the lead, playing the system.

It's a real problem in cases involving disability from disorders that are not visible or illness that fluctuates. But it should be a problem for the assessor, not the applicant. It is for the assessment mechanism to develop tools that are sufficient to accurately triage and bottom out a person's level of functional disability. In doing so it's vital to understand that it's perfectly possible for someone with a severe psychological disorder to be just as housebound as, for example, a blind person or someone with a dense stroke.