Before
the days of grills and modern cookers, the cheese was melted in front
of the fire and bread was toasted on both sides with butter spread on
one side and the melted cheese poured on top.
Sometimes beer, pepper
and salt were mixed with the cheese.
In 1747
a cookery book gave a recipe for as bread
toasted on both sides and a slice of cheese, the same size as the bread,
also toasted on both sides and laid on the buttered bread.
The same
book had "Welsh Rarebit" made in the same way but with mustard rubbed
on the cheese.
"English Rarebit" on the other hand had a glass of red
wine poured over the toast before the cheese was added.
Take your pick!