This is a list of parliamentary constituencies in London from the coming into force of the Representation of the People Act 1918 until the next reorganisation of constituency boundaries which came into force at the 1950 general election. The constituencies introduced in 1918 were based on the metropolitan boroughs of the County of London that had been created in 1900. Outside London constituencies were formed by the grouping of municipal boroughs and urban and rural districts that had been created by the Local Government Act 1894.