What does the expression "in with the loaves, out with the fairy cakes" mean?

I dimly (from childhood) remember this as a baking allegory. When ovens were parts of cooking ranges heated by fire rather than precisely controlled gas or electricity, they might first be heated to high temperature for the bread making. If the fire was reduced, the oven would later be at a lower temperature suitable for light cake making. If something went into the oven at the same time as the bread but was forgotten about, it would later be discovered when the cakes came out. Being there so long in such an unplanned manner, it was ruined.

This seems to apply to the described incident. The allegory has force if you are familiar with the difficulties and practices of cooking on the old ranges, but is unlikely to be understood by young people who only know the joys of almost instant temperature control. The speaker pictured in the article, Mr Bliss, is clearly of a similar generation to my own, and would know this.