Passage: After the Labour Party won the 1945 election, Eden went into opposition as Deputy Leader of the Conservative Party. Many felt that Churchill should have retired and allowed Eden to become party leader, but Churchill refused to consider this. As early as the spring of 1946, Eden openly asked Churchill to retire in his favour. He was in any case depressed during this period by the break-up of his first marriage and the death of his eldest son. Churchill was in many ways only "part-time Leader of the Opposition", given his many journeys abroad and his literary work, and left the day-to-day work largely to Eden. Eden was largely regarded as lacking sense of party politics and contact with the common man. In these opposition years, however, he developed some knowledge about domestic affairs and created the idea of a "property-owning-democracy", which Margaret Thatcher's government attempted to achieve decades later. His domestic agenda is overall considered centre-left.

Question: Who did Eden become the head of?
the Conservative Party