Also the shoes. At secondary school they need, as a minimum: smart school shoes (which they'd never wear or be seen dead in for any other purpose), trainers for general PE, then some kind of specialist sports shoes (football, rugby, hockey etc). Some schools even insist on two different kinds of sports boots, as well as the trainers.
Add to that at least one pair of casual shoes or trainers for them to wear outside school, then seasonal footwear eg wellies or flip-flops or whatever.
Assume all pairs have to be replaced on average twice a year, irrespective of how much wear they've had, due to growth. If you have a girl then you might be lucky and her feet might stop growing around size 4 or 5 so you can still get them non-VAT rated and make them last a bit longer. Boys' feet though just keep on & on growing! Size 6 & above no longer count as kids' shoes so you're paying the full price for 5-6 pairs of men's shoes every six months until they turn 16 or even 18. If you have multiple DC this is hundreds of £££ every time!
I understand of course that they would need to have some kind of shoes anyway, that exercise is important and specialist sports footwear can't be avoided. But to add uniform on top of all that just shows a total lack of sensitivity to families' financial realities.
I've always thought the 'levelling' thing was nonsense anyway. It's often quite easy to tell which children come from better off families because either they have the logo items when others have generic, or they've got fancier bags, lunchboxes, coats, or whatever. Not to mention being able to replace uniform regularly so it's always shiny and new, while families with less money can't afford to do this. It's never stood up as an argument and now less so than ever.