... Bladud must have been the traditional founder of Bath before Geoffrey made him so.  The name Bladud however is British, and it is therefore difficult to conceive of the growth of the legend in Saxon or early Norman times.  Its connection with Bath ought to go back to the period when Bath and the surrounding country were still in British hands.  Who was this Bladud, this famous necromancer, this discoverer of the hot springs and the mythical founder of Bath?  No light is thrown on the question by the name which, in its present form, could only signify "wolf-fighter."  Geoffrey of Monmouth, however, makes Bladud the father of Leir—the Welsh Llyr, Irish Lir, whom Professor Rhys has shewn to have been the old Keltic God of the Sea.  His father, therefore, will have been a god also, and, like his son, connected with the watery element.  Professor Sayce then proceeded on the lines of comparative mythology to show that the god of the hot springs of Bath was a form of the Sun-God—that Sun-God of the nether world for whom Professor Rhys has shown the Kelts had a special predilection.  This god answers exactly to the description given of Bladud by Geoffrey.  Further proof of this is found in the fact that the name Bladud appears mroe than once in Geoffrey's mythical history of the island.  Mr. Sayce summed up his conclusions as follows:—1. That Bladud was originally the British God of the hot springs at Bath, and a local form of the Sun-God symbolized in Roman times by an orb-like human face, bristling with flames.  2. That the name and attributes of the god transformed into an earthly prince like the other personages of Keltic mythology formed the subject of a folk-tale at Bath before the age of Geoffrey of Monmouth... (Bye-Gones, Relating to Wales and the Border Counties, 1889-90). 

... Bladud reigned twenty years.  He built Kaerbadus, now Bath, and made hot baths in it for the benefit of the public, which he dedicated to the goddess Minerva; in whose temple he kept fires that never went out nor consumed to ashes, but as soon as they began to decay were turned into balls of stone.  About this time the prophet Elias prayed that it might not rain upon earth; and it did not rain for three years and six months.  This prince was a very ingenious man, and taught necromancy in his kingdom, nor did he leave off pursuing his magical operations, till he attempted to fly to the upper region of the air with wings which he had prepared, and fell down upon the temple of Apollo, in the city of Trinovantum, where he was dashed to pieces.
    After this unhappy fate of Bladud, Leir (Lear), his son, was advanced to the throne, and nobly governed his country sixty years.  He built upon the river Sore a city, called in the British tongue, Kaerleir, in the Saxon, Leircestre.  He was without male issue, but had three daughters, whose names were Gonorilla, Regau, and Cordeilla... (The British History of Geoffrey of Monmouth,  1842)