In this week’s Budget, touted as the last before the UK leaves the EU, the Chancellor allowed himself only one reference to the B-word. It seems that Philip Hammond is more concerned with the state of the nation’s mental health than with Brexit.

Hammond announced £2 billion for mental health funding to come out of the additional £20 billion that Theresa May had previously earmarked for the NHS. The money will go on a 24-hour mental health helpline, more ambulances for those suffering from severe mental health problems and “crisis cafes” for people to access mental health support without going to a hospital.

A proportion of the money will go to shore up a proposal first mooted in the government’s children and young people’s mental health Green Paper: that schools should have dedicated mental health professionals and support teams. Hammond’s announcement confirms this aspiration and signals that all schools will be expected to have a member of staff, most likely a teacher, who has received training and assumes responsibility for children’s mental health. These mental health leads will be overseen by NHS clinicians and will aim to help children with “mild and moderate mental health problems.”

Critics have protested that the government’s proposals do not go far enough and that more money will be required. Labour leader Jeremy Corbyn was quick to claim the new money is “only half of what is needed”. Norman Lamb MP, chair of the Commons Science and Technology Select Committee, pointed out that the funding will not increase the proportion that the NHS spends on mental health, adding: “It is not enough.” Others have argued that tech companies, rather than the taxpayer, should be funding efforts to tackle mental illness in schools.

What is the purpose of schools?

Yet before so much as a penny of Hammond’s £2 billion has been spent, awareness of mental health problems in children has been heightened. Many will argue this can only be a good thing. But treating all children as if they are mentally fragile can rapidly become a self-fulfilling prophecy as parents, teachers and pupils themselves come to interpret the everyday experiences and emotions of childhood and adolescence as signs of the mental health problems they have come to expect.

Young children who talk of feeling stressed or anxious are using a vocabulary that has been taught to them by well-meaning adults. The idea that all children are, to some degree, vulnerable to mental health problems becomes accepted as normal. Increased awareness will lead to a growing number of children being diagnosed as suffering from mental health problems. As a result, the professionals employed in schools will no doubt appear to be meeting a huge unmet need for support. This, in turn, is likely to lead to calls for yet more practitioners and more funding. Why should we assume that only one mental health practitioner per school is sufficient? Why not one per year group? One per class?

Offering mental health support to children appears humane, kind and fair. But when all children come to be perceived as potentially mentally vulnerable then interventions that appear supportive actually create the very problems they seek to address. There can never be sufficient funding or services in place as demand will always outstrip supply. But plans to have a dedicated team of mental health professionals in schools raise far more than financial issues.

Schools have traditionally been concerned with education, not health - yet there are no proposals for every school, including the smallest primary, to have access to dedicated chemistry or music teachers. Prioritising mental health shifts the purpose of schools away from teaching and learning. Tests, exams, setting and streaming, enforcing discipline and expecting high academic standards are at odds with a more therapeutic approach to education. Teachers warning about the dangers of stress in one lesson might find it hard to justify a routine spelling test in the next class for fear it might provoke the anxiety they want to avoid.

Education should encourage children to look outwards to the world but an obsession with mental health encourages children to look inwards to their own emotions and self-esteem. It’s not just that getting children to reflect on how they feel about maths takes time away from doing maths, it also narrows their horizons and restricts their knowledge to their own limited experiences.

A mental health professional in every school will shift the focus of schooling from education to therapy, and in the process children will come to be seen as fragile and vulnerable, rather than robust and resilient. In the meantime, we have reports of children with special educational needs and disabilities being excluded from schools and children with existing mental health problems waiting up to 18 months for an appointment with the child and adolescent mental health services. If the chancellor has cash to spare, perhaps it would be better spent there.

Joanna Williams is head of education at Policy Exchange