I bought a bit of baking powder and baked a batch of biscuits. I brought a big basket of biscuits back to the bakery and baked a basket of big biscuits. Then I took the big basket of biscuits and the basket of big biscuits and mixed the big biscuits with the basket of biscuits that was next to the big basket and put a bunch of biscuits from the basket into a biscuit mixer and brought the basket of biscuits and the box of mixed biscuits and the biscuit mixer to the bakery and opened a tin of sardines.
Source: Coronet Magazine, August 1948
(Said to be a diction test for would-be radio announcers: To be read clearly, without mistakes, in less than 20 seconds)