Half of schools are in a trust. Most trusts have one school.

We counted this because the advice everyone repeats, sell to the trust and not the school, is wrong in both directions depending on which trust you've walked into.

Start with the headline. Of the 24,553 open England schools in our copy of GIAS, 12,410 sit under a trust. Call it half. That much is uncontroversial.

Then the shape gets odd. There are 2,135 open trusts with at least one open England school in them, and 960 of those, very nearly half, run exactly one school. Another 458 run between two and five. A single-academy trust has a board, a scheme of delegation and all the paperwork of a group, and it still buys like one school, because it is one school.

The concentration sits at the far end. 111 trusts run more than twenty schools each, and they hold 3,572 between them. The fifty largest hold 2,096, which is more than twice what all 960 single-school trusts hold put together. United Learning Trust alone has 98 open England schools, then REACH2 with 65, and St Gabriel the Archangel and Delta Academies on 64 each.

So the mean trust size of 5.8 schools describes almost nobody. It's the average of a thousand ones and a hundred giants.

So build your target list from the school count, not the label. A trust with more than twenty schools almost certainly has a central procurement function and someone whose actual job is contracts. A trust with one school has a business manager who's also doing the timetable and the fire drill. Those aren't the same sale, and the word trust sits on both of them.

What GIAS won't tell you is where the decision actually gets made. It records the legal link, not the scheme of delegation, and plenty of mid-sized trusts centralise payroll while leaving catering or IT entirely to the head. We can show you the structure. Somebody still has to pick up the phone and find out.

Method. Counted from the daily GIAS extract we import, restricted to open England schools and open trusts with at least one open England member. Trust size is the count of open England member schools, so a trust with schools in Wales or a closed academy reads smaller here than on its own website.