My father is almost 89 yrs of age and has a holiday booked for Spain next month and has had Travel Insurance since time of booking. During a scan for another matter is was discovered he had a reasonably small aiortic aneruism. It does not seem significant enough to see a Vasicular person immediately and is just being put on a waiting list. He has heard the word in the passing but it is of little significance to him and unaware exactly what this is so is blissfully anaware of any seriousness. I do understand that if this ruptures it is likely to be fatal but in all honesty I know that is the way he would want to die.....quickly! Also at his age it is unlikely they will put him through the very major surgery this would involve as his chances of surviving this would be minimal. He is joining my daughter and her husband on this holiday and as yet they do not know anything is wrong. Since he doesn't know about this is he still covered?

If he is aware of the fact that he has a new medical condition - even if he is unaware of the seriousness then he will have to tell the insurance company and see if he can be covered for it.

If he decides to cancel the trip then he should be covered for the costs incurred.

Each policy is different but FYI here is the Norwich Union wording:

If, between booking a Trip and the departure date or the renewal date (whichever is sooner) You receive medical advice for a potentially serious illness or injury Your policy will cover You for cancellation of Your Trip. However if You still wish to travel We will advise You if You will be covered for
Emergency medical and associated expenses, Hospital benefit or Abandonment claims relating to this condition.

Also: Have your daughter and son in law checked with THEIR travel insurance provider that they are covered if your father dies/ requires treatment (even before the latest diagnosis?). Forgetting about family member's health is a major reason why some policies don't pay out.