The two cities lie just 20 miles apart, but the rivalry between their two football teams is fierce.
It can divide families and it can dominate office talk on a Monday morning.
As Pompey and Saints prepare to meet in the league on December 17 – for the first time in almost six years – their long rivalry is now being celebrated by fans and players alike at an exhibition called A Game Of Two Halves.
At Westbury Manor Museum in Fareham, a town very much in the middle geographically when it comes to allegiances, the room is divided with red on the left and blue on the right.
Pictures of Pompey legends Jimmy Dickinson, Alan Knight, Peter Crouch, Linvoy Primus and Herman Hreidarsson are strategically placed on the wall on one side.
On the other side Dean Hammond, Rickie Lambert, Jose Fonte, Kelvin Davis and Lee Barnard grace the Saints wall.
Old programmes, hats, scarves and football shirts are proudly displayed along with a ticket for Pompey’s FA Cup final victory over Cardiff in 2008.
And in the centre of the exhibition stands the map of south Hampshire, providing an opportunity for fans to make it clear which side they stand with the use of red and blue stickers.
And people from around the world will be able to make their mark by contacting the museum through its Facebook website.
It means wherever anybody is around the globe, they will be able to get in touch and place a red or a blue sticker on their location.
Tom de Wit, curator at the museum, says: ‘We want to know where the dividing line is. It’s got the whole of south Hampshire on it. Supporters can put on a red or a blue dot for where they live.
‘In Fareham itself we will see where the division between the red and blue is.’
The exhibition will give fans of both Pompey and Saints the opportunity to celebrate their intense rivalry through Subbuteo, Playstation games, watching archive footage of the clubs, or even simply just reading about their history.
Whether you still celebrate Pompey’s 4-1 win over the Saints at Fratton Park back in 2005, or reminisce about knocking Pompey out of the cup at St Mary’s in 2004, the exhibition gives fans the chance to look back on a rivalry going back generations.
And as many players have gone on to play for both sides, so have managers gone on and stood in both dugouts, such as Alan Ball.
In 2004, Harry Redknapp famously left Pompey and went on to manage Saints, who got relegated to the Championship. Harry returned to Pompey a year later to save them from relegation, and then helped to win the club the FA Cup for the first time in 69 years.
Tom says he was inspired to create the exhibition by thinking back to the jubilant scenes of May 2008, when Pompey famously won the cup and paraded it around the streets of Portsmouth.
Harry Redknapp was mostly forgiven by Pompey fans by that point, but some had remained bitter.
‘Just seeing the passion down in Southsea and seeing how people were really confused about Harry Redknapp was really interesting,’ he says.
‘People still said they didn’t trust him. I see Harry Redknapp as a Clint Eastwood sort of character. We don’t know if he is good or bad.
‘Here, we’re in the middle. Fareham in particular is somewhere where even in the same office or the same family you’ll have people supporting both Pompey and Saints. It can get nasty but mostly it’s good-natured.’
In the early days the rivalry was a lot more friendly, with fans from both clubs often cheering on the other team as well.
When Pompey won the FA Cup back in 1939, it’s understood that many of the Saints fans abandoned the club’s game at The Dell and went up to Wembley to cheer on Pompey.
The museum had had a great deal of help from both clubs to create the exhibition and supporters even helped by donating pieces of memorabilia from over the years.
‘We deal with history here at the museum,’ says Tom.
‘The rivalry itself is rooted in history. You can’t understand the history of this area without understanding the history of these clubs. It’s been going on for 100 years. Rivalry is really important. If there was no rivalry there wouldn’t be any passion.
‘But it’s about keeping it healthy. I’m absolutely confident that most of it is healthy because so many people share offices or it’s within their families. The nastiness is a small part of it.’
Tom is hoping that the exhibition can encourage people to get more involved in the local football scene.
He says: ‘We want to inspire people.’
The exhibition kicks off on Saturday to tie in with Fareham Borough Council’s Tour of the Town, which celebrates a year until the start of the 2012 Olympics.
It will be officially opened by the Mayor of Fareham, Councillor Trevor Cartwright, at noon, and will be attended by several former Pompey players. The exhibition, which is free, will run until October.
· Westbury Manor Museum is in West Street, Fareham. Call 0845 603 5635 or go to www3.hants.gov.uk/westbury-manor-museum
There are many theories as to how rivalry grew between Pompey and Saints.
But the most well-known is that it started when a group from the South Coast Union Men of Southampton supposedly crossed the picket line when Portsmouth dockers went on strike in the 1950s.
It is rumoured that this is where the expression ‘Scum’ comes from, still used as a derogatory nickname for Saints fans by those who support Pompey.