Boys do find ways to avoid detection such as "stamping the hair down with water", but it doesn't always work. A Class XII student of Apeejay Park Street who had got an undercut during his Puja vacation was hauled up when school reopened and taken to the principal.

"I had got the sides trimmed to 1mm and so it had become shorter than usual and prominent. Before returning to school, I visited the barber to trim the middle part so that the undercut became less obvious. But I still got caught," recounted the 17-year-old.

Class IX student Aryan Sethi of South City International School too had "tried out an undercut", but his teachers didn't quite agree that it looked "cool". The 14-year-old was asked to trim the middle portion to match the sides.

So, what is the yardstick for a hairstyle that meets the requirements of school discipline without making boys feel cut off?

"In the old days, we would emphasise on neatness in all aspects... and one of these was no hair falling over the back of the collar. On inspection days, points would be awarded to boys based on how they turned up," said John Mason, a former principal at St. James'.

The rules were unambiguous too: hair above the collar, sideburns halfway down the ear and sides above the ear. For some principals, the yardstick was: "I should not be able to grab the hair from behind."

In the late 1980s and '90s, the big trend was the Amitabh Bachchan style with middle-parted long hair neatly covering the ears. Elvis Presley's Pompadour had been one of the popular hairstyles to be seen in two decades before that. Long, curly hair like Michael Jackson's used to be copied too, but not flaunted.

Schools would cope with the occasional hair horror with a pull and a cut. "Some teachers would grab the hair from behind and lift it upwards, which is very painful. And the school barber was a terror. The boarding warden, the PT master and the house master would always make sure hair was cut down to the acceptable length," recalled a former principal.

When Mason was the principal of St. James' from 1978 to 1992, he had his own way of dealing with bad hair days on the campus. A typical exchange between the principal and the errant student would go like this:

Mason: "What are you doing this Saturday?"

Student: "Nothing, sir,"

Mason: "Well, then you will have some time to go to the barber!"

St. James' has since done away with the campus barber because of complaints from parents, but hair continues to raise the hackles of the school.