In 1822 the most part of the territory of Sudan was under Egyptian rule. In the second half of the 19 century Sudan was administered as a British colony. But at some point the British wanted to reunite all the land so they started this process under the Egyptian leadership by Muhammad Ali Pasha.
From 1924 and until 1956 Sudan was administered by British as two separate territories. The march towards Sudanese independence started in 1952 when the Egyptian Revolution began. The revolution led to the abolishing of the monarchy in 1953. The leaders of Egypt believed that they could stop British domination in Sudan only in they officially abandoned their claims of sovereignty over Sudan. On the other hand British supported Sudan politically and financially. This led the polling process that ended with the composition of a democratic parliament in Sudan and the election of the first Prime Minister, Ismail al-Azhari.
The official ceremony that marked the gaining of independence was held on 1 January 1956 at the People's Palace. That day both the Egyptian and British flags were lowered and the new Sudanese flag was raised by Ismail al-Azhari.Remind me with Google Calendar