Until the day pupils were due to receive their certificates, Mr Tuck believed the problems were confined to fewer than 1 per cent of candidates. "I spent the day giving radio and television interviews with the ground all the time shifting beneath my feet."
He told The TES Scotland in an exclusive interview that the authority's hardware and software systems were not to blame, nor was schools' reporting of marks. The difficulties lay with data input and management. He still does not know why so many certificates were incomplete or erroneous.
The SQA's computer needs had been described as "more than a bank's and less than those for air traffic control". But the new system had had barely more than a year to be run in because of delays and change in what Higher Still would demand of it.
When in June and July the absence of data from some schools was noticed and an "audit trail" established, no "golden bullet" was found - that is, there was no single identifiable cause for the problems. By then he was chairing daily meetings of senior staff. Because fewer than 1 per cent of certificates seemed likely to be delayed or incomplete, the target date of August 9 for sending them out was adhered to.
As one of the architects of Higher Still, Mr Tuck is anxious that the SQA's problems do not lead to precipitate changes. "The debate should not be sidetracked." Pupils and parents had broadly welcomed the new courses.
Meanwhile 50,000 candidates for HNC, HND and Scottish Vocational qualifications are awaiting their certificates within the next month. For some, a place in higher education will depend on the SQA's promptness and accuracy.