Natasha Radmehr: Silly, surreal, and slightly bonkers, Channel 4 is my kind of national treasure

“Daaaah, daaaah, dah-dah!” It’s 1989 and I’m three years old, sitting rapt in front of the TV as the rainbow-hued Channel 4 ident bursts onto the screen. I theatrically perform these “dah-dah-dahs” along to the music every time the coloured blocks collide, or so my parents tell me.