Tales abound in the folk history of the British Isles, mostly Scotland and Ireland, of a form of beer made from heather. The Picts, Scots and Irish are all said to have brewed it at one time or another, with some Irish sources suggesting that the recipe was obtained from the Danes. Since beer requires some form of sugar or another in order to ferment, it is generally presumed that either the heather bells (flowers) were simply used as an adjunct, much like hops, or that honey made from the heather bells was used as the fermentable sugar in the brew.
However, the following excerpt from William Vaughan's "Naturall and Artificial Directions for Health", published in 1600, seems to imply otherwise:
What shall poor men drink when malt is extreme dear? They must gather the tops of heath, whereof the usual brushes are made, and dry them, and keep them from moulding. Then they may at all times brew a cheap drink for themselves therewith. Which kind of drink is very wholesome as well for the liver as the spleen, but much the more pleasant if they put a little liquorice unto it. There is another sort of drink of water and vinegar proportionately mingled together, which in summer they may use.
There is an interesting article in
Homebrew Digest #1224 by
Ken Miller in which he excerpts
Bickerdyke's 1889 text
"The Curiousities of Ale and Beer", that can be found by searching the Homebrew Digest archives at http://www.hbd.org. There are a number of other articles in various issues which touch on the topic as well.
There is at least one brewery selling a product they call "heather ale", which goes under the brand name Fraoch (the Irish word for heather). They state on the bottle that their recipe dates back to 4000 BC, which may very well be nothing but a marketing ploy. However, it is a tasty brew just the same, with a lightly flowery flavor in it, and tastes much the way one would imagine that heather beer would taste, so it may very well be the genuine article. I believe Fraoch heather ale is a product of Scotland, but you may be able to find it in specialty beer stores outside the British Isles. It is sold in pint bottles.