Our next door neighbours have 2 DC, one Y5 age, one YR age. They walk to school unaccompanied by an adult every morning. Sometimes they are joined by a friend, who is also Y5.
The journey to school is short - around 150 m along pavement along a main road, crossing 3 side roads. Over a pedestrian crushing. Another 30m or so into school. Takes about 2 mins! School encourages children to walk to school if they can from Y5, in prep for moving up at Y6 (we have middle schools).
My concern is more about a 9 year old being responsible for a 4 year old (both dc have birthdays in the summer holidays) crossing a fast, busy road. There are pedestrian crossing lights, but there are still accidents on that crossing every few years (I have lived here over 20 years).
I would offer to take them with my DC, but I start work at 8 am and my dc go to breakfast club first. Seeing the girls next door go off alone slightly worries me every morning, but I don’t know if I am being overprotective of someone else’s dc! We don’t really know the people next door, dd has picked up on their ages/birthdays by playing ball with them over the fence!!