Lots of things happen with wassail.

First of all it is not just one thing it is four.

1.Linguistically it is a toast derived from the languages of scandanavia.

2.It is an ancient ritual of blessing fruit trees generally apples.

3.It is one of many pan european and pan british isles door to door customs (see al lloyd)

4.Wassail in the hall is a Loving cup tradition wherein inside a hall the loving cup is passed from one to another with toasts and kisses being exchanged. (sometimes the cup has 12 handles and ribbons...)

So take your pick.... sure the linquistic origins are scandanavian and the first use recorded in the british isles involved the saxon king vortigean (sp?) but.... the customs of wassailing themselves seem to be more ancient than any saxon influence.

Take a look at my pages for more on this topic:

http://www.geocities.com/CapitolHill/5567/wassail.html

Enjoy!

Conrad