"There's obviously an element of cachet in being in Oxford," says Mr Gordon, "and they are living in an Oxford college, which many students like the idea of. Indeed, some parents sometimes worry that it will distract them, but frankly the students don't have time. They are immersed in the course. There's no let-up at all, and no opportunity for distractions."
Mr Gordon is not exaggerating. The brochure description of the course structure looks exhausting - lectures, group seminars, essay-writing classes, a review of past examination papers and mock exams. Reading through the daily schedule for Cherwell's young crammers, who concentrate on one A- level or two GCSEs during the course of a week, is even more alarming. Working in groups of six or seven, students start each morning at 9am with an hour's trial examination, and then work right through the day till 6.45pm. Even after dinner, they are expected to get their heads down and prepare yet more work for the following day.
"It's very, very intensive," admits Mr Gordon, "They are very tired at the end of the day." The brochure puts it more bluntly: an early night is recommended, it warns.
Much of their labour is what Mr Gordon describes as "fine-tuning" for the demands of public exams in June.
"The normal school syllabus concentrates on the material, but not how to get it down on paper in a given time," he says. "In part, though, you're being tested on your ability to sit an exam, and that's the ability we try to develop during the week."
Despite the slog, there's no doubt that spending a week in Oxford is a real attraction for many. For the spring vacation, St Hilda's college, renowned for its lovely gardens and enviable position by the river Cherwell, plays host to 70 to 80 students from Oxford Easter Courses.
"Students really like the idea of being in Oxford," says its principal, Edwin Osborn. "They do seem to find it stimulating living in a college and having the experience of being an undergraduate - although undergraduates probably don't work quite as hard!" Indeed, he had found the foretaste of Oxford life has inspired a number of his students to apply to the university for their degree.
Oxford Easter Courses prides itself on its small and friendly atmosphere. Its tuition groups are confined to two or three students, and total numbers rarely exceed 70 or 80.
"We deliberately try to keep it small," says Mr Osborn, who has run the courses from home with his wife Jane since 1993. "It means they can make sure that their time is only used on exactly what they need and want to do."
They also stick purely to A-level courses. "A-level students are that bit more mature and motivated," believes Mr Osborn. "They really want to do the work, whereas those doing GCSEs are often kicked there by their parents."
Unlike other tutorial colleges, Oxford Easter Courses eschews mock examinations. Mr Osborn, who used to be a tutor at another institution, believes they are self-defeating.
"The students are too tired and too busy, and they have not had a chance to assimilate the material properly yet," he says. "It's simply not fair to assess them like that. And if they don't do very well, it can really knock their confidence."
Another advantage of coming to Oxford to do your revision lies in the quality of tuition, says John Farquhar, principal of the Centre for International Education (CIE), which runs 30-hour intensive courses in all GCSE and A-level subjects.
"As well as being qualified and experienced teachers, the vast majority of our tutors are Oxford graduates, so the standard of tuition we can offer is particularly high," he says. "But overall, the atmosphere here is highly academic - you can't avoid it. I do think that the mystique of Oxford appeals to students and parents. Maybe they feel that some of the magic will rub off on them. It is part of the overall experience that we offer."
CIE courses aim to cover most of the syllabus in a week, with students working in class groups of six to 10. The course attract a cross-section of pupils from both state and private schools, and one of the main aims of the tutors - apart from filling gaps in their subject knowledge - is to to try to give them more confidence, especially in the technique of taking exams.
CIE and the other tutorial colleges undoubtedly succeed in their aims; all report glowing testimonials from past students and their parents. It's not difficult to see why. Judging by how hard their students are expected to work, Oxford crammer courses are a baptism of fire. Sitting your GCSEs or A-levels must be a doddle by comparison.
Cherwell Tutors (01865 242670) is running A-level and GCSE courses from 21 March to 9 April, 1999. One-week study and residence at Hertford or Jesus colleges costs pounds 495.
Oxford Easter Courses (01865 311517) is running A-level-only courses from 27 March to 11 April, 1999. One week residential study at St Hilda's College costs pounds 550.
Centre for International Education, Oxford (01865 202238) runs GCSE and A-level courses from 15 March to 23 April, 1999. One week costs pounds 300; accommodation, which is extra, costs around pounds 100 for a single room.Reuse content