Whitehall is the name of a street in London in which there are many government offices. You can also use Whitehall to mean the British Government itself.
...people with banners marching down Whitehall.
Whitehall said that it hoped to get the change through by the end of June.
Whitehall in British English
(ˌwaɪtˈhɔːl)
noun
1.
a street in London stretching from Trafalgar Square to the Houses of Parliament: site of the main government offices
2.
the British Government or its central administration
Whitehall in American English1
(ˈhwaɪtˌhɔl; ˈwaɪtˌhɔl)
noun
1.
former royal palace in Westminster, London, destroyed by fire (1698)
: also Whitehall Palace
2.
the British government
Whitehall in American English2
(ˈhwaɪtˌhɔl; ˈwaɪtˌhɔl)
street in Westminster, south of Trafalgar Square: site of several government offices