I'm so glad someone else never though of doing this, we saw a soreen toastie loaf in tesco and both had the same reaction. It works really well though, goes all soft and melts the butter, also smells of cake which is never a bad thing
I've also tried it with coffee (ok but not great), adding a couple of spoonsful of marmalade (very nice) and even a measure of whisky (not peated) for a special twist.
That's the beauty of old recipes like this, you can always try something new.
You used to be able to buy a spicy corned beef, I distinctly remember the tin having red flame effects on the label.
It was superb, but evidently didn't sell we'll as it appears to have been discontinued. :-(