So providers and comparison sites are working on improving the sort of questions asked and technology is being improved to make sure premiums are fair, accurate and competitive.
But despite the importance of being able to use comparison sites, Alan Knowles, managing director of Cura Financial Services, comments: "There is no single 'best' insurer when it comes to offering cover for people with a history of mental illness.
"Speaking to somebody who has suffered with a mental health issue should be done with care and understanding, and just selecting the cheapest provider from a comparison site may not always be the most suitable choice."
Mr Cadger also states: "Mental health conditions represent the most frequent medical disclosure in financial protection applications at Scottish Widows, more so than back disorders, hypertension and asthma, and we consider these carefully and sensitively, in the same way we would for any physical health conditions."
Paying out
Figures from Grid and the ABI also revealed 11 per cent of claims paid out in 2017 for individual income protection were for mental illness.
This compares with 10 per cent for cancer and 30 per cent for musculo-skeletal. According to Ambika Fraser, head of proposition at Unum UK, "most providers pay out on claims for clinically diagnosable mental health conditions, when it prevents an employee from being able to do their job."
Yet when it comes to paying out, as well as for coverage, it is perhaps significant that Mr Harvey believes there is no one particular stand-out insurer working in this field.
He says: "There's no-one better at dealing with mental health than another. It all depends on the specific circumstances as to which insurer would be more favourable."
This is why Ms Fraser makes a distinction between providers who simply pay out - and those "quality insurers" who actually help companies "prevent mental health absences in the first place - and this is where employers can find the most tangible difference in providers", she notes.
And again, this is starting to change. Mr Cadger comments: "There is a commonly held misconception that someone living with a mental health condition will not be offered insurance, or at worst, the provider will not pay out a claim."
However, he claims 95 per cent of consumers who declare they have a mental health condition will be offered life cover, "giving them reassurance they can still receive cover that will pay out at claim stage."
Education
But more needs to be done to get the message across to the public and to their financial advisers.
