Cyril, who was an old mate of mine when he lived in Leeds, would insist, "Chicken on a raft is not poached egg on toast, or even fried egg on toast. It's fried egg on fried bread! Proper job!!"
Tone
.,,.

The fact that Cyril wrote the song does not in itself make him the sole or definitive authority on what the phrase meant. I daresay some seamen or crews would use it for fried on toast or poached on toast, even if those Cyril served with used it mainly of fried on fried. Some probably would even have used it for any egg however cooked served on any sort of cooked bread.

That, in case some haven't noticed, is what folklore is ~~ something of which it is unwise to claim an absolutely definitive version, whoever may postulate it.

~M~