Hi

The owner of a school talks to a certain teacher and says:

When, in 1870, it became law for every child to attend
school, that for the whole area – Renham, Catermarsh and
Walwyk – was, very wisely, I think, situated at Renham.

This sentence is puzzling to me. The guy says that when in 1870 it was necessary for kids to go to school, in his opinion it was a wise decision for the whole area. He mentions Renham, Catermarsh and Walwyk and then again says "situated at Renham" at the end. I read it again and again and don't get it.

Children in those days were still deemed capable of
walking three miles morning and afternoon, and our
school could have closed, but by that time it had become a
family hobby. And so it has remained.’

--- What does walking to school three miles have to do with closing the school?
1) "That" in this paragraph refers to "school". So the sentence says that it was wise that the school was situated at Renham.

2) I need some further context to be sure but perhaps there were 2 schools and when the new school opened in Renham, there was no need for the local school ("our school") to remain open as the children were capable of walking 3 miles to school (in Renham presumably).
Hi

So it says: When in 1870 children had to start going to school, it was a very good idea, I think, that the school was situated in Renham and not in Catermarsh or Walwyk.

Is that right?
Teachers: We supply a list of EFL job vacancies
Yes, that's the idea.
Ivanhr I need some further context to be sure but perhaps there were 2 schools and when the new school opened in Renham, there was no need for the local school ("our school") to remain open as the children were capable of walking 3 miles to school (in Renham presumably).
So he probably means that he's happy that the new school was open in Renham, but at the same time that new school was a threat to his own private school.
I don't know that he was HAPPY about it, but he agreed that it was the best decision for those in the area.

I don't have to be happy about something to recognize it as a good idea for others.
Students: We have free audio pronunciation exercises.
Perhaps he saw it as a threat, I don't know. It seems, though, that they were reluctant to close the old school because, as they said, it had become a family hobby. As a consequence, it has remained open.