About a kilometre west of Tiananmen Square and the compound housing China's top leaders in central Beijing stands a large unmarked building. No sign hangs at the entrance to indicate the business conducted inside. The occupant's phone number is unlisted; calls from the building do not display an incoming number identifying their origin, just a string of zeros.

As the Communist party today marks 60 years in power, however, the occupants of the office complex will be quietly celebrating as well. Little known even within China, the body based there and known as Zhongzubu - the Central Organisation Department - has emerged from the country's economic upheaval of the past three decades as indispensable to the party's hold on power.