Her parents, Alan and Rosemary, felt as she did. Sarah had failed to win her place by only one grade. Instead of the three Bs she needed, she had a B in Latin, a B in history but only a C in French.
'We were terribly disappointed,' says Mrs Robertson. 'French was her best subject and her teachers expected her to get all As and Bs.'
The university was adamant: no grade B, no place. Her parents contacted Sarah's school, Leicester Grammar. 'We found that all five pupils who had taken French at A-level had done less well than was expected,' says Mrs Robertson. They tried to persuade the school to send all the results back to the University of London Examinations and Assessment Board. When the head said no, the Robertsons appealed through the school on Sarah's behalf, paying the pounds 50 required for a full remark by the chief examiner.
A few days before Sarah was due to begin a course at a polytechnic, a letter came from the exam board to say that the papers had originally been marked incorrectly and that she had now been upgraded to a B.
Though her own daughter's story ended happily, Mrs Robertson believes pupils whose parents have neither the means nor the knowledge to tackle the appeals system may not be so lucky. 'I still feel the school should have sent back all the results,' she says.
After Sarah received her upgrading, Mrs Robertson sent a letter of protest to the school's chairman of governors. He replied that as a matter of principle it was not right to request a remark or the exam system would break down and the school would acquire a reputation as 'whingers'.
John Sugden, head of Leicester Grammar, said: 'The school was happy to appeal on Sarah's behalf because we thought she had been hard done by. However, the head of department felt it was not fair on the board to appeal on behalf of the group as a whole.'
Only a small minority of candidates in A-level exams request a remark - though the numbers have been rising as parents become more aware of their rights - and the success rate is low. Last year, the Associated Examining Board, the largest one, had 179,000 exam entries and 4,700 queries about the results. Eventually 430 marks were changed.
Dissatisfied candidates should first talk to their school, then an appeal can be made (by the school) to the examining board if results are out of line with the school's expectations. Each board offers services ranging from a simple clerical check to ensure the marks have been added up properly to a full remark of all the papers. If a remark is requested, all the candidate's scripts will be collected and sent to the chief examiner who will also, if required, write a report on why the grade has been awarded.
Fees vary, but the University of London board this year charges pounds 2 for a basic clerical check of the marks and grade boundaries; pounds 10 for a breakdown of marks for each part of the exams plus a clerical check; pounds 33 for a clerical check and remark, and pounds 52 for all the former plus a report from the chief examiner; coursework for a group can also be remarked.
Scripts are sent back to the board with the chief examiner's new or unchanged grade. Sometimes the remark is lower than the original, but the board never drops a candidate's grade. If a candidate or a school is not satisfied, boards will often provide further checks. Fees are refunded if the appeal is successful, except that paid for a chief examiner's report.
For the past two years, the final arbiter in appeals has been the Independent Appeals Authority for School Examinations. The authority can only examine procedures; it can recommend that a board looks at the papers again if it thinks a candidate has been wronged, but it cannot remark papers.
Candidates wanting to appeal to a board about this year's results must do so by 30 September.