Portsmouth South was created in 1918 via a split in the Portsmouth constituency.
Portsmouth South is the "harbour end" of the city of Portsmouth, and contains the famous Royal Navy Portsmouth Base dockyard, the small seaside resort of Southsea, and Portsmouth University. Portsmouth South is slightly poorer than its neighbour Portsmouth North overall and also has greater income inequalities; Fratton in particular has areas of significant deprivation by south east England standards. It also has a high student population with most demographic statistics within the average range.
Portsmouth South used to be a safe Conservative seat, but a 1984 by-election upon the death of Bonner Pink changed all that. That was won by the SDP's Mike Hancock, who was a Labour, then SDP councillor in Fratton. Mr Hancock was unseated by only 205 votes in 1987 by David Martin, and Mr Martin held on again to Mr Hancock's next challenge, this time by the almost-as-narrow margin of 242 votes. Mr Hancock recaptured it in 1997 during the Conservative meltdown and held it for the next 18 years. In 2014 he resigned from the Liberal Democrats after a civil suit alleging sexual harassment was brought by a constituent of his; he contested the seat as an Independent in 2015 but received a derisory 716 votes; that year the Conservatives' Flick Drummond captured it. Surprisingly in 2017 she was defeated by Stephen Morgan, who became the first ever Labour MP for Portsmouth South. Against the national trend, Mr Morgan managed a further 3.9% swing against the Conservatives due to tactical voting from the Liberal Democrats, increasing his 2019 majority to almost 3 1/2 times that of his 2017 majority. At a local level this seat's wards are generally divided between Labour and the Liberal Democrats, with Easney & Craneswater being the only reliably Conservative ward in the constituency.
This is a good description of the seat's history.
Portsmouth South is arguably one of the most interesting in the South East region - and not just because it is my home seat!
It is a very diverse constituency; there is significant wealth in parts of this seat e.g. property close to Gunwharf, Craneswater, parts of Central Southsea. But there's also significant deprivation - Fratton, Buckland etc. Added to the mix, you have a large student population found in the heart of the constituency.
This leads to a volatile electorate - and this has been reflected in the recent election results (with all three main parties being in power here since 2015).
Though I am not a Labour supporter, Stephen Morgan does seem to be very visible in the constituency. People like the fact that he's from the area. Fairly or unfairly, voters connect with him (or indeed Mike Hancock in his early years) a lot better than a parachuted candidate. And this appeared to be part of Flick Drummond's downfall in 2017; she had little presence, especially outside of Southsea.
The increasing number of students, as well as the high number of public sector workers, mean that the Conservatives have a tough battle re-gaining this seat. Expect a comfortable hold in 2023/2024.
And Portsmouth South looks increasingly grim for the Lib Dems. In the recent general election, they just managed double digits - and some of their remaining local 'strongholds' look increasingly marginal (e.g. Milton, Fratton, St Jude). And let's not forget they lost Central Southsea last year (their candidate was meant to succeed GVJ as leader of the council).