The UK in the era of comprehensive state education has had very different views on school size depending on the age of children.
A typical local authority provides small schools for 5-11 year olds. This means they can be close to the homes of the parents. The Head can know all the children in the school and can do some teaching. It cuts the strain on local roads, and even allows the possibility of more children walking to school.
That same typical authority may think secondary school children should attend schools with 1200-1500 children on the school roll. This means they draw on children from a very wide area. It increases the strain on local roads. Head teachers often do no teaching, as the administrative and personnel tasks are all consuming. Whilst Heads and senior teachers would claim to know all the children, in practise their knowledge must be patchy at best in some cases. Only a small fraction of the pupils can walk to school.
The main argument for large secondary schools relates to student choice of subject, especially in the sixth form. A large school can afford a wider range of specialist teachers, offering a wider range of subjects. I think we need to ask if this is sufficient reason to justify building more of these large schools. It would be possible at sixth form stage for pupils from School A to go School B for a specialist course that School A cannot offer and vice versa. It is also possible to draw on the resources of local sixth form Colleges, FE Colleges and local universities for the occasional student who wants to offer an A level outside the mainstream.(I remember having reading rights at the local university library in the sixth form and attending some public lectures). In practise core subjects like maths, english, science, history and economics remain the most popular and can be staffed in a smaller school.
An ancillary argument is that a large school is more economic, allowing concentration of the overhead costs for a larger number of pupils. This argument, however, is not thought relevant in the case of primary education. It also ignores the fact that a smaller school can employ part time staff to carry out functions that need to be full time in a larger establishment, or can share administrative back up with other similar schools.
So what are the advantages of smaller schools? The first is they are less expensive to build, less of a major commitment. The second is a wider range of smaller schools offers more choice. The third is that in practise most pupils will come from the surrounding area, so travel is easier and transport strain and cost less. The fourth is they can develop more sense of community and common achievement. They could have a whole school assembly, and teachers and the Head will have more knowledge of every pupil.
I am not suggesting that big schools are necessarily bad schools – far from it. I know some very good large schools. I do, however, think more small schools in the mix would extend choice, and would offer some solutions to some of our problems. It represents the quickest way of expanding choice and cutting transport stress when capital money is limited.