It's the same with Thatcher when she was Education secretary. She didn't want to stop the milk in schools but was forced to by HM Treasury (so it was presumably the Chancellor wot did it, really).
Not surprisingly, lefties hate this inconvenient truth.
Stopped by the Tories in junior schools, and it was finally stopped in infant schools by Shirley Williams when she was still Labour.And the fact that Labour had already stopped it in secondary schools....
2-1 to Labour, then.