@iris Yeah! American tablespoons and teaspoons went metric in the late 1990s, and it was very smooth because mostly nobody noticed. Teaspoons barely changed at all, but tablespoons got smaller.
As I understand it, American Old Tablespoons are the same as current Australian tablespoons, and are about 1/3 larger current international tablespoons. And just by chance I have an old tablespoon as well as my normal modern tablespoons.
Given how it came out I at very least wasn't wrong to have the more milk. Doing the conversion to a modern tablespoon for this recipe is very easy - it'd be four instead of three.