Dr. Barnard, who created the first critical illness cover in 1983, said: If you die at 30, life insurance was more important, but if you get a critical illness at 55, or 45 when you are at the height of your earning ability and you have an operation and survive another ten to 20 years, then Critical Illness Insurance was more important.

Where workability decreases and the ability to provide for your financial needs diminishes, I think that the critical illness policy is much better.

This view is based on a much higher national life expectancy, alongside rapidly developing medical research that makes it possible to diagnose previously fatal conditions and prolong the patients life. A patient diagnosed with a serious illness but living for a further twenty years would receive a payout on their critical illness cover that they would not get on their life insurance policy.

Critical illness insurance has risen in scope and popularity over the last few years to cover 58 conditions as opposed to 4 when it was first introduced. It now includes functional diseases such as multiple sclerosis and an estimated 12 million adults and children are covered by a critical illness policy.

However, there have been many stories in the press concerning aggrieved policy-holders whose insurers have reneged on their critical illness cover. An investigation carried out last summer by the BBCs One Show discovered that many conditions that the policy-holders believed were covered were excluded and that the terms of the policies required meticulous medical records to be kept.

A spokesperson for the show said: Its no mean feat remembering every single visit to the doctor but thats what insurance companies expect you to do when youre filling out a critical illness form - and its the kind of question thats catching a lot of people out. The first thing is to remember that insurance companies are profit-making enterprises. The onus is on you to make sure that youve covered all your bases before you get ill, rather than expect any goodwill from the company when disaster strikes.

Dr. Barnard is keen to highlight the number of successful cases of critical illness cover payouts: All I hear when I walk around here is that 20% of critical illness claims are not paid. However, the fact is that 80% are paid. Statistics such as 20% of the claims are not being paid are not strictly true because 20% of the claims should not be paid because they don't fit the criteria.

He has also outlined what changes he would like to see in the form and structure of critical illness insurance. As things stand at the moment a lump sum is paid out to the holder upon diagnosis, but Dr. Barnard would prefer it to be paid out in stages as the illness increases in severity: Diagnosis is getting better and most people have treatment and then walk out. If they continue to receive full payout at diagnosis, the cover will become so expensive it will no longer remain affordable for those that really need it.