A local secondary school appears to have done this. Like most they were in the blazer/tie uniform, then quite recently moved over to the trendy, relaxed sweat and polo combo- but it seems they're now back in a (different) blazer and tie set-up.
Wonder why? Incidentally, it's not a school that closed and reopened as something else, and it's in Hampshire, not inner London.
Our school ditched blazers and ties about 6 years ago, but I must say, teh DC do look a bit scruffy! And I liked having a blazer at school- so many pockets!