Dress up for this date...
But now it is staff who will have to pull their socks up when inspectors are given the power to report on the standards of teachers' dress.
Staff wearing jeans or trainers, or with excessive piercings and tattoos, could plunge a school into special measures under the new inspection regime.
Office for Standards in Education spokesman Kevin Klein said: "It is important for teachers to project a professional image and set an example for students by maintaining good standards of dress.
"The days when a teacher could wear the same tweed jacket with leather elbow patches day after day are over."
Inspectors say they found extensive evidence that staff are dressing inappropriately, including one RE teacher who took lessons wearing an old Black Sabbath T-shirt.
New guidelines, modelled on the dress code at the Institute of Directors'
Pall Mall club, are intended to give them a more businesslike look.
Men will be expected to wear a dark suit and tie, and women will be told not to wear anything "too short" while avoiding a "frumpy" appearance.
But Joe King, from the Campaign for Traditional Education, said the new rules did not go far enough and called for a return to the mortar-board and gown. "Some teachers can't even tie their own shoelaces, let alone produce an acceptable Windsor knot," he said.
The new regime will come into effect on April 1 next year.