I've been told that Ofsted like to see such things on the wall and for students to know exactly what level they are, what they're working towards and how to get it, because it makes the kids engage with their learning. In an inspection, the kids pulled out by the inspectors are expected to be able to tell them exactly that.
The result is tables posted up in every classroom showing the baselines, results from each data drop, targets for the end of the year and end of Keystage. Not in a ranking, just alphabetical order and the numbers/levels. That it's nothing to be embarrassed by, that kid has started from a higher level, but has a higher target to reach, etc, etc - and the so called super smart kid might very well be at a higher level at the beginning, but if they haven't moved from level 3+ in the year, they've not achieved as much as the lower level kid who has managed to get up from 2- to 3 in the time.
Personally I think it's shit. I didn't need to know I was top of the class because the sarcastic comments if I answered a question made it pretty clear and if you're academically thick as mince, you know it damn well without having it up on the wall for others to point out your place
But then again, until somebody explained to me that registers were in alphabetical order based upon the sex and surname of the children, I was always disappointed that my name wasn't the first called in the morning and in the last few rows of lists. If they'd been done on the basis of ability, I'd have been at the top - and it's not as if I could do anything about my name, either. Except if it were based upon rapid fire times tables tests. I had been lazy and just memorised a mental image of the column of numbers (8, 16, 24, 32, 40, etc) because I'd far rather be doing something like music or art. Didn't affect my maths skills in the long run, seeing as I have taught the subject and can answer rapidfire without ever having to sit and learn them by rote. [shrug]
Anyhow, the teacher has probably been told they have to do it. It's not about singling anyone out or embarrassing them.