Research by travel insurer AllClear found that a mere 10.5 per cent of people aged 45-70 correctly guessed that an accident or emergency in Europe could end up costing an average of between £5,000 and £6,000.

The proportion of 66-70 years olds who got the right answer was just 7 per cent.

Overall, 14 per cent of respondents thought the bill would come to between £500 and £1,000.

According to the report, costs vary widely between countries. While the average emergency medical claim from a trip to Spain is £6,500, in France the average claim is much lower at £2,600. Continent-wide, the average claim is £5,348.

Garry Nelson of AllClear said: “It can be very expensive to fall ill abroad, and our new research demonstrates that the vast majority of people planning on taking a summer break this year have no real idea of how much it could cost if they are unfortunate enough to have a medical emergency.”

While Britons have little understanding of how much the emergencies ultimately cost, they are firm in their conviction that travel insurance firms discriminate against older travellers.

Some 93 per cent of respondents in the oldest age group thought that travel insurance providers were “ageist”. The figure fell to half for all age groups, with only 2.5 per cent strongly disagreeing.

Nelson added: “It’s a pretty damning conclusion. More and more people in older age groups look forward to travelling abroad, and it is a shame that they believe insurers discriminate against them on the grounds of their age.”