>>> most of us went home
That's where there's an important change, Hc4361. Over the past decade or so I've worked on loads of travel surveys, often monitoring the movements of pedestrians, cyclists and vehicles close to schools. I've seen countless pupils arriving for school at the start of the day and countless pupils leaving school at the end of the day but, throughout the whole of that period, I've not seen a single child going home for lunch.
Shortening the lunch break is often part of the reason why schools now close earlier at the end of each day. The secondary school I taught at (in the 70s and 80s) originally ended the school day at 3.30pm. By cutting the lunch break from 70 minutes to 50 minutes, and by moving the start of the day from 8.50 to 8.40, we could knock half an hour off the end of the day, so that the school closed at 3.00pm. (A nearby secondary school was even more creative in rearranging their hours, enabling them to end their day at 2.40pm).
I've not noticed so much change in the school day within the primary sector though. The primary school I attended in the early 60s ended its day at 3.30pm. The primary school where I now live ends its day at 3.25pm.