I spent hours one day going through the census books for the area, street by street and yes, institutions seem to have separate books. I found the ones for a Little Chapel Street (now Caxton) which had the headmaster and his family, but not for the school students. I just need more patience. Doggedness? Sigh. There’s not much logic between book numbering and so many streets have changed names or disappeared, so I have to sort that out, find the relevant area on the map and see if it’s near where the school is.