Perhaps the police expected the strike to turn into a battle as teachers went to war to protect their pensions. Judging by the enormous number of officers lining the roads of central London, the Met predicted violence.
The entrance to Downing Street was barricaded and lined with armed officers. Did David Cameron expect teachers to turn up at his front door?
Even more officers sat waiting in minivans parked off almost every side road near Parliament and Westminster Abbey. Riot police marched around, but their skills were not needed, so they wore baseball caps instead of helmets.
In the end, the highly visible police presence looked frankly bizarre. Many of the strikers were smartly dressed middle-aged teachers strolling peacefully down the closed-off roads. They looked more likely to be going on a shopping trip to Marks amp; Sparks to stock up on Per Una cardigans than hell bent on bringing down the Government.
These were experienced professionals, furious enough to take action for the first time in their careers. They walked through the streets of the capital carrying placards in the hope someone would take notice.
And people did. News crews hovered above the march in helicopters. Men with cameras milled about, keen to get them to talk. Photographers stood by eagerly, hoping for some fights to start.
But nobody knew for certain if the one person they did want to talk to, Michael Gove, was watching events from his office just yards from the rally.
Towards the end of the day, attention turned to a hard core of protesters who remained. Their youth made them unlikely to be teachers, but some had picked up official ATL placards. They may have been up for a scrap, but the vast, peaceful majority were not.
This group certainly seemed to feel as if they had made their point once the march came to the end. So how to celebrate a busy afternoon of industrial action? Popping home to finish off some marking appeared to be the order of the day.