http://en.wikipedia.org/wiki/Haj_Amin_al-Husseini
"Following the death of Amin's half-brother, the mufti Kamil al-Husayni in March 1921, the British High Commissioner Sir Herbert Samuel pardoned al-Husseini. He and another Arab had been excluded from the general amnesty, six weeks earlier, because they had fled before their convictions had been passed down. Elections were then held, and of the four candidates running for the office of Mufti, al-Husseini received the least number of votes, the first three being Nashashibi candidates. Nevertheless, Samuel was anxious to keep a balance between the al-Husseinis and their rival clan the Nashashibis.[41] A year earlier the British had replaced Musa al-Husayni as Mayor of Jerusalem with Ragheb al-Nashashibi. They then moved to secure for the Husseini clan a compensatory function of prestige by appointing one of them to the position of mufti, and, with the support of Ragheb al-Nashashibi and Sheikh Hussam Jārallāh, prevailing upon the Nashashibi front-runner, Sheikh Hussam ad-Din Jarallah, to withdraw. This automatically promoted Amin al-Husseini to third position, which, under Ottoman law, allowed him to qualify, and Samuel then chose him as Mufti"
Apparently while appointed by the Government the Mufti were selected from the first three in a election. Samuel's chose Haj Amin al-Huesseni.
Further the British administration then created the SMC (Supreme Muslim Council ) and appoint Al-Hussenni to the head of the SMC and passed the control of large funds to his hands.
The Rise of Al-Hussenni to a position of power was solely the result of the British Administration, who appointed against the traditional custom to his position, then handed much more power and money into his hands. It was control the opposition by subverting it. It was used in other British Colonial settings, takke your outspoken critic co-opt through official appointments and monies.