When Sister Brigid Halligan was first told that inspectors would be visiting her school in three days' time she thought her staff were playing a practical joke.
Teachers at Bellerive school in Liverpool had been warned they might have as little as 48 hours notice before the inspectors arrived.
But none of the teachers at the all-girls Roman Catholic school had expected a surprise inspection last month, only weeks after they volunteered to trial the new short-notice system.
Sister Brigid, the headteacher, said: "I had already made plans for the Tuesday when they were coming, including attending an admissions appeal panel, but I had to cancel. The short notice is all very well in theory, but in practice it is different."
Despite her reservations, Sister Brigid said the new-style inspection was less stressful overall and gave a more accurate picture of her school.
All of Bellerive's teachers had spent a training day earlier evaluating the school's work and its senior management team had worked evenings for a week to fill in an online form.
Sister Brigid said that, although the self-evaluation had been labour-intensive, staff would not have to repeat much of the paperwork in future.
The team of seven inspectors visited the school for three days, spending between 15 and 30 minutes in lessons before moving on to see how other pupils in the same year group were studying.
The inspectors this week gave Bellerive an excellent report which praised its leadership, teaching, and "outstandingly high" standards of behaviour.
They were so impressed by its self-evaluation they only changed grades on two aspects of the school's work - they felt it deserved even higher marks.