Wilson and Blackett began a search for what was known as The Greatest Work of the Cymru' - Cifrangon. This is a massive, hollow, man-made hill concealed somewhere in Wales (similar to Silbury Hill). Treasure hunters in Wales have long sought this fabled hill in which, it is believed, lie several objects of tremendous historical and archaeological value, many of which may be covered in gold. For centuries, the old Welsh knew themselves to be descended from the Lost Tribes of Israel , and Cifrangon is believed to be the place in which the Ark of the Covenant - containing the broken slabs on which the Ten Commandments were written by Jahweh - was concealed. The men first discovered the site in 1981.The bit on the use of the Google Earth terrain model is quite amazing (guys take a quick zip over to Hatshepsut's Temple in Luxor and see what the terrain model there shows).
They apparently also have published their ideas about the ancient Welsh discovering America, summarised here:
Research into claims that the Welsh settled in mid-western America in antiquity led to Wilson and his colleague, Baram Blackett, accepting invitations from American supporters to visit US sites of historical significance in 1994. The visit led to several television appearances and the deciphering of alphabetic inscriptions claimed to be in the old 'Coelbren' alphabet. Wilson also concluded that the many snake mounds in the American Mid-west were of ancient Khumric-British construction. Whilst in America, the two men were also commissioned to produce a detailed genealogy for the Bush family (friends and supporters of President George H. W. Bush).This is also discussed on the bad Archaeology website: Madoc in America Bad archaeology