In all my life I’ve never heard it called the “heel” of the bread. In Australia (at least in FNQ) we always called that the “crust”. Whilst my partner hates it, the crust was the most coveted piece growing up because it never really counted as a “slice”

“Who ate all the bread!” “Nah I only had 1 piece and the crusts” “That’s okay, which Motherfucker ate the bread then!”