Midlesex is one of the 39 historic counties of England and the second smallest by area. The low-lying county contained the wealthy and politically independent City of London on its southern boundary and was dominated by it from a very early time. The county was significantly affected by the expansion of the metropolitan area of London in both the 18th and 19th centuries; such that from 1855 the south east was administered as part of the metropolis. When county councils were initially introduced in England in 1889 around 20% of the area of Middlesex, and a third of its population, was transferred to the County of London, and the remainder formed a smaller county, in the north west, under the control of Middlesex County Council.