Some years back I was hired to turn a health education document written in civil service-speak into a better approximation of English.

In essence it was setting out the then Scottish administration's health priorities.

Some way down the line, happily pre-publication, it came to our notice that, while dental health got a name check, mental health had accidentally been missed out entirely. Oh, how we didn't laugh.

That was then. But now? Now there are still fears that mental healthcare – the perennial Cinderella service – is still looking for a proper outfit in which to go to the funding ball. Last week, a persuasive but alarming report emerged from the Centre for Economic Performance at the LSE about the current English experience.

It made some powerful points about the totally false economy of not providing adequate access to treatment for those with mental illness, and the huge cost of failing to diagnose conditions, particularly in childhood, which have a devastating impact in areas such as crime further down the road.

The authors' most damning statistics were those which highlighted the fact that for under-65s almost half of all ill-health was mental in origin, yet only one-quarter of those suffering from illnesses such as depression or anxiety were likely to be in treatment.

The price of failing to diagnose and treat is huge, not only in terms of suffering – it's estimated that mental pain exceeds the physical variety by 50% – but in real hard cash. Their calculation was that GDP loses out by more than 4%, which translates as some £52 billion per year.

That's partly down to the greatest incidence of mental illness being in the 15-to-44 age group which makes it the primary factor in almost half of all absenteeism at work, and the numbers on incapacity benefit.

They suggest too that one-third of all families will have a member currently suffering from mental health issues. Think about one-third of all families currently having someone with a broken leg. But of course we don't think about mental health in those terms.

Yet two thoughts alone should concentrate our minds: the mortality rate is the same as that for smokers and more than for obesity, and 30% of crimes are committed by people who had undiagnosed mental health problems as children.

This timely report also flags up the under-acknowledged fact that so many unexplained physical symptoms have their origins in mental ill health. It argues passionately for more trainee GPs to experience psychological therapies as part of their rotations, and more psychiatrists to be schooled in aspects of general medicine.

But the overwhelming message is that, because of the overlap, treating mental illness can be largely self-financing. Patients offered a course of psychological therapy have a very good chance of a cure, and represent a huge saving from not developing debilitating stress-related physical conditions.

But instead there is evidence of money earmarked to increase access to therapies being siphoned off to shore up funding gaps in other parts of the English primary care trust system.

The health structure in Scotland is quite different, of course, but mental health problems are no respecters of political boundaries.

Chris O'Sullivan, senior project officer for the Scottish Mental Health Foundation, is entirely in agreement with his southern colleagues about the complexities of physical and mental symptoms, noting that, in addition to physical symptoms being the product of mental illness, many patients with long-term chronic physical illness develop emotional problems as a result.

He also points out that patients with mental health issues may fail to have physical problems diagnosed, perhaps because they are less likely to notice symptoms, their medication masks the symptoms or sometimes previous experience of accessing services makes them fearful of seeking help.

New Scottish policies on mental health are currently being developed after consultation in the sector and one of the so-called "heat targets" will centre on the provision of psychological therapies.

"But the Scottish emphasis is likely to be a little different", says O'Sullivan.

"The English model tends to focus on cognitive behavioural therapy, whereas the Scottish policy is likely to be wider."

He chairs the trustees for Action on Depression in Scotland which utilises guided self-help and online therapies and trains other groups to do the same. Developed from the Living Life to the Full programme devised by Professor Chris Williams at the University of Glasgow, these interventions aim to build life skills and wellbeing across a whole range of contexts including areas such as autism.

O'Sullivan is at pains to point out that professionals in both England and Scotland share the same driving motivation to have parity of treatment in mental and physical services.

"But I do think that, because Scotland has a smaller eco-system, it's been easier post-devolution for both organisations and users to access policy-makers and offer them real-life examples. So I think I could describe myself as cautiously optimistic about the Scottish situation."