It found that a fifth of the population (21%) would not be financially secure if their household’s main earner was unable to work.

As national cancer awareness campaigns for Prostate Cancer, Ovarian Cancer and Brain Tumours take place in March, Scottish Widows said millions of Britons are under-protected should serious illness strike.

It said more than a third (36%) would resort to raiding their savings if they were unable to work. Despite this, only 32% of people have life insurance, and just one in ten (9%) have taken out critical illness cover.

Prostate cancer is the most common cause of cancer in men in the UK and one in eight men will be diagnosed with this illness during their lifetime, while around 20 women are diagnosed with Ovarian cancer every day, according to Cancer Research UK.

Scottish Widows paid out almost £4.5m in critical illness claims relating to prostate cancer, ovarian cancer and brain tumours in 2015, which collectively accounted for almost one in ten (9%) of all cancer claims that year. Almost two thirds (63%) of all critical illness claims were due to cancer.

The average age of diagnosis for prostate cancer in 2015 was 57, while the average age for ovarian cancer was 47. More than half (55) of brain tumour claimants were male, the youngest being 30 years of age.

The cancer awareness campaigns coincide with the publication of a new report – No Small Change – by Macmillan Cancer Support, which reveals that thousands of middle-aged people in the UK are being forced to borrow money from their parents because of the cost of having cancer.

Macmillan estimates that more than 30,000 people with cancer in their 40s have borrowed money from their elderly parents, and more than 2,000 have moved in with their parents or parents-in-law after having to sell their house.

The charity says that 28% of people with cancer of all age groups – an estimated 700,000 individuals – are vulnerable too because they have no savings to fall back on. And for 83% of cancer patients, lost income and increased expenditure brought about by the disease costs them an average of £570 a month.

Scott Cadger, head of underwriting and claims strategy at Scottish Widows, said: “Critical illness insurance can provide a significant financial boost at a time of emotional stress and financial difficulty, and can really help families who are struggling to come to terms with the impact of cancer.

“At a time when welfare reform is resulting in significant changes to benefits, families need to do all they can to protect themselves in the event of the unexpected happening.”