Indeed, this was taught to me in the late-90s in A-level Economics as absolute undisputed fact. The path forward had become clear whereas it hadn't been understood previously. It annoys me now, looking back and knowing it's such an incredibly naive take on how capitalism works. Was it naivety on the part of the teacher, or propaganda slipped into the curriculum? I don't know.

A separate issue worth mentioning is that the water companies (as opposed to trains, gas, electricity, Royal Mail, etc) don't fall under this because they were privatised as regional monopolies. The government didn't even (pretend to) attempt to create competition.