From the Wikipedia page [1] - deleted June 2013.

The Blitz ciphers are a set of 3 pages of paper covered in unidentifiable symbols, so called because they were originally discovered concealed in the wall of an East London cellar within a wooden box, that was only exposed due to German bombing during the Second World War. The ciphers have only come to light recently after having been passed down to the nephew of the initial discoverer, who shared pictures of them via the internet in an effort to try and crack the code. Of course, there is a possibility that the pages are a modern hoax, but as of January 2012 this remains to be seen.

The first page, possibly a title page, is headed by a large symbol within a circular plaque/boss and contains 3 large paragraphs of symbols, of which the first two are quite faded. In addition to this, smaller "text" surrounds and annotates the larger paragraphs, pointing out and underlining some of the larger symbols.

The second page contains two unusual diagrams; a drawing of an octagon containing symbols within the diagram and at each point, and an odd tree-like diagram with a circled area towards the bottom again containing and surrounded by more symbols.

The third page is covered by a 20x20 square grid, with a cipher symbol in each square and red dots at certain junctions.

Further details can be found here on the Cipher Mysteries website pages [2] and [3], and also here [4], and there are a number of other websites.