These boundaries have been considerably changed since 1970, when Islington returned three MPs and shared another with Hackney. This reflects the depopulation of central London on a lowering of adult occupancy of households and the local authority has replaced tower blocks. The core of the constituency was the area north of Seven Sisters Road and Camden Road. At , it is the smallest UK Parliamentary constituency. At the Fifth Periodic Review of Westminster constituencies begun in 2012 the seat was approximately 1,300 electors below the electoral quota and the highest concentration of elector density nationally. The criteria of successive reviews emphasise equal electorates as well as restricting seats to one or, if unavoidable, two local authority areas.