It used to be the preserve of teenagers with itchy feet and few responsibilities. But these days, it is their 50-something parents who are more likely to take a gap year. The number of "grey gappers" picking up their backpacks and setting off on foreign adventures has soared. One in four over-55s has either been on a gap year in the last five years or is planning to take one, according to a report. But the research also revealed that the gap year is "no longer an option for many post A-level students", with fewer than one in five plotting the same sort of escape - and many blaming the soaring costs of going to university. The research comes after official figures showed thousands of students are ditching the traditional year-off adventure after leaving school. Just 6,000 18-year-olds have deferred a firm offer of a place on a university course for this year, according to admissions service Ucas. Last year, 20,000 did. The slump is due to the crippling cost of a university education, with fees due to rise from ￡3,290 a year to as much as ￡9,000 in 2012. Students starting their degrees in 2012 are expected to face an average debt of ￡56,000 on graduation, compared with around ￡27,000 if they began their studies this September. As a result, many do not want to spend money on a gap year - and the grey gapper appears to be filling the void left by their children. The report found that the most common destinations for older travellers are Australia, New Zealand, America, Singapore and Spain. And for the more adventurous, India, Vietnam and Hong Kong are also popular. Dr Ros Altmann, director of over-50s travel and financial specialists Saga, explained that grey gappers typically want to leave their children behind and enjoy the adventure with their spouse. She said: "It is often the first thing that a lot of people do when they have retired. They go on a very long holiday."