On 16 August 1833, he was appointed minister at the court of Spain. Ferdinand VII died within a month of his arrival at Madrid, and the infant queen Isabella, then in the third year of her age, was placed on her contested throne, based on the old Spanish custom of female inheritance. Don Carlos, the late king's brother, claimed the crown by virtue of the Salic law of the House of Bourbon which Ferdinand had renounced before the birth of his daughter. Isabella II and her mother Christina, the queen regent, became the representatives of constitutional monarchy, Don Carlos of Catholic absolutism. The conflict which had divided the despotic and the constitutional powers of Europe since the French Revolution of 1830 broke out into civil war in Spain, and by the Quadruple Treaty, signed on 22 April 1834, France and England pledged themselves to the defence of the constitutional thrones of Spain and Portugal. For six years Villiers continued to give the most active and intelligent support to the Liberal government of Spain. He was accused, though unjustly, of having favoured the revolution of La Granja, which drove Christina, the queen mother, out of the kingdom, and raised Espartero to the regency. He undoubtedly supported the chiefs of the Liberal party, such as Espartero, against the intrigues of the French court; but the object of the British government was to establish the throne of Isabella on a truly national and liberal basis and to avert those complications, dictated by foreign influence, which eventually proved so fatal to that princess.