When originally created in 1918, the South division of the Parliamentary Borough of Leicester was defined as including the municipal wards of Aylestone, Castle, Charnwood, De Montfort, Knighton, Martin's, and Wycliffe.
The initial report of the Boundary Commission for England dated October 1947 and published in December 1947 recommended that Leicester retain three seats, including a revised Leicester South constituency consisting of the wards of Aylestone, De Montfort, Knighton, North Braunstone and Spinney Hill, giving an electorate of 67,574 as of the review date of 15 October 1946. When the Representation of the People Bill enacting the Commission's recommendations was debated in the House of Commons, the Government brought forward amendments at Committee stage on 24 March 1948 to allow 17 more constituencies in England. Home Secretary James Chuter Ede announced that the Boundary Commission would be invited to consider an additional constituency to each of nine Cities, including Leicester. The Government issued a White Paper proposing the new boundaries which created new borough constituencies of Leicester South East and Leicester South West in place of Leicester South. The Boundary Commission recommended no alteration to the proposals, and the revised constituencies were therefore enacted.
In 1969 the Second Periodical Report of the Parliamentary Boundary Commission for England reduced Leicester from four seats to three, and recreated Leicester South as a borough constituency consisting of the Aylestone, Castle, De Montfort, Knighton, Spinney Hill and Wycliffe wards of Leicester.
Minor boundary changes were made as a result of the Third Periodical Report of the Boundary Commission in 1983. Ward boundaries having changed, the constituency was defined as including the Aylestone, Castle, Crown Hills, East Knighton, Eyres Monsell, Saffron, Spinney Hill, Stoneygate, West Knighton and Wycliffe wards. The new constituency took in about 3,000 voters who were previously in other Leicester seats. No changes were made in the Fourth Periodical Report of the Boundary Commission in 1995, and in the Fifth Periodical Report of the Boundary Commission in 2007, the constituency had only minor changes with 73 voters being added from Leicester West.
Leicester South is a varied constituency. It contains some of the most pleasant and affluent areas of Leicester such as Stoneygate, Knighton and Aylestone, as well as more deprived areas such as Saffron and Eyres Monsell. The centre of Leicester, also within the constituency, is more ethnically diverse than the southern part of the area. The seat also contains HMP Leicester and both of Leicester's universities.
This was once a Conservative vs. Labour marginal seat and was held by the Conservatives between 1983 and 1987. It moved strongly towards Labour through the 1990s and was considered a safe Labour seat until the death of Jim Marshall in 2004. The subsequent by-election was fought under the shadow of the Iraq war and won by the Liberal Democrats from third place, making Parmjit Singh Gill, at the time, the only Liberal Democrat MP from an ethnic minority. He held the seat for a year before being defeated by Labour candidate Sir Peter Soulsby at the 2005 general election. Soulsby subsequently resigned to become elected Mayor of Leicester in 2011, giving Leicester South its second by-election in the space of seven years; the second by-election was safely held by Labour.
The constituency was first created in 1918, abolished in 1950, and reconstituted in 1974.
Leicester South has over the past few decades seen demographic and economic changes which have altered the balance of the constituency. The seat saw close contests between Conservative and Labour candidates in the 1980s, with Labour MP Jim Marshall losing the seat by just 7 votes to the Conservatives in the 1983 general election but regaining it in 1987. In subsequent elections a general trend indicates a Labour majority has accumulated that since 1987 it has become more of a safe seat however it has not sent all MPs since.
Sir Peter Soulsby, who had been the unsuccessful Labour candidate at the 2004 by-election, won the seat at the 2005 election and was re-elected in 2010. Sir Peter resigned to fight the election for the new position of Mayor of Leicester in 2011, triggering a by-election on 5 May 2011, coinciding with the referendum on the voting system.Jon Ashworth was elected as his successor, holding the seat for the Labour Party.