On marching into London he was openly received by the rebel barons and citizens of London and proclaimed (though not crowned) king at St Paul's cathedral. Many nobles, including Alexander II of Scotland, gathered to give homage to him. However, in signing the Treaty of Lambeth in 1217, Louis conceded that he had never been the legitimate king of England. The House of Plantagenet takes its name from Geoffrey Plantagenet, Count of Anjou, husband of the Empress Matilda and father of Henry II. The name Plantagenet itself was unknown as a family name "per se" until Richard of York adopted it as his family name in the 15th century. It has since been retroactively applied to English monarchs from Henry II onward. It is common among modern historians to refer to Henry II and his sons as the "Angevins" due to their vast continental Empire, and most of the Angevin kings before John spent more time in their continental possessions than in England. It is from the time of Henry III, after the loss of most of the family's continental possessions, that the Plantagenet kings became more English in nature. The Houses of Lancaster and York are cadet branches of the House of Plantagenet. This house descended from Edward III's third surviving son, John of Gaunt. Henry IV seized power from Richard II (and also displaced the next in line to the throne, Edmund Mortimer (then aged 7), a descendant of Edward III's second son, Lionel of Antwerp). The House of York claimed the right to the throne through Edward III's second surviving son, Lionel of Antwerp, but it inherited its name from Edward's fourth surviving son, Edmund of Langley, first Duke of York. The Wars of the Roses (1455–1485) saw the throne pass back and forth between the rival houses of Lancaster and York. The Tudors descended in the female line from John Beaufort, one of the illegitimate children of John of Gaunt (third surviving son of Edward III), by Gaunt's long-term mistress Katherine Swynford. Those descended from English monarchs only through an illegitimate child would normally have no claim on the throne, but the situation was complicated when Gaunt and Swynford eventually married in 1396 (25 years after John Beaufort's birth). In view of the marriage, the church retroactively declared the Beauforts legitimate via a papal bull the same year. Parliament did the same in an Act in 1397.