The trend for schools "spoon-feeding" pupils to pass exams is creating high achievers who struggle to cope with the rigours of studying at Oxbridge, an academic has warned.
Counselling services at Oxford and Cambridge universities are reporting "year-on-year" rises in the number of youngsters seeking help because they lack resilience when faced with challenges in their studies.
The issue was raised this week by Professor Guy Claxton at the first major conference of Whole Education, a group that wants schools to focus on more than exam success.
Professor Claxton, whose book, Building Learning Power, has won an international following, said: "I talked a little while ago to the directors of the two student counselling services at Oxford and Cambridge.
"They are seeing a year-on-year rise in the number of young people who arrive apparently confident, with four to five As at A-level, but lacking resilience, lacking the ability to cope if they do not get great success. Fifteen to 20 per cent of Cambridge students will find their way to the counsellors' waiting room - 1,200 did so last year at Oxford.
"They are very clear, these two people, that these high-achieving youngsters are becoming more and more vulnerable because they are being spoonfed more and more efficiently by their teachers to get them through their exams. There is more modularisation, more packaging, and learning is more chopped up."
Schools should promote resilience alongside other qualities including curiosity, reasoning power and empathy, Professor Claxton said.
His comments follow a Sutton Trust report which found that state school pupils with the same exam results do better at university than their private school peers.
Senior figures at both Cambridge and Oxford's counselling services said they agreed with Professor Claxton, but added Oxbridge students also faced other pressures, including worries about getting a job.
Mark Phippen, head of the Cambridge University counselling service, said: "We are quite aware of the number of students who are obviously very academically able but paradoxically lack confidence.
"That may come about from no longer being a large fish in a small pond, but also people being less prepared to take on challenges without others helping them out."
Alan Percy, clinical director of the Oxford University counselling service, said: "The kind of conversation I often have with a lot of clients, or hear from students, is that students often don't grasp the full meaning of learning.
"Learning is finding out something that you did not know and struggling with it. It's almost as if, if they do not know something immediately they feel as though they are failing."
Brian Lightman, general secretary of the Association of School and College Leaders, said the root of the problem was not modularisation of exams, but league tables. "The issue is that if you are just teaching to the test, that's bad teaching and it's not developing the right kind of resilience in young people."
Other groups that concerned Professor Claxton were "low achievers" who wanted to drop out of school quickly and policy-makers who could not see beyond categorisation of teaching as either "traditional" or "liberaltrendy".