What is Whitehall?
Whitehall is (noun) 1. a street in London, leading from Trafalgar Square to the Houses of Parliament, where there are the offices of several government departments As you walk down Whitehall you pass Downing Street on your right. 2. the British government and civil service Whitehall sources suggest that the plan will be adopted. There is a great deal of resistance to the idea in Whitehall. Whitehall mandarins top British civil servants
source: Easier English, Student Dictionary Upper Intermediate Level