Foyle, which is essentially Greater Derry, has remained one of the few SDLP outposts in the face of a rising Sinn Féin tide elsewhere in Northern Ireland.

The Westminster seat has been held by the SDLP for many years: first by John Hume; and, since 2005, by Mark Durkan. Since the advent of Assembly elections, the party has also bested Sinn Féin in this predominantly nationalist constituency.

However, there have been signs that dominance being on the wane. In the last Assembly elections, in 2011, Sinn Féin came within 500 votes of its nationalist rival, taking two seats on 13,200 votes, to three for the SDLP with 13,699.

The last remaining seat has always been a unionist one. The Democratic Unionist Party has ruled the roost here for many years.

The constituency is flush to Donegal and is mainly urban, though with a rural hinterland. It includes many areas with high levels of poverty and deprivation, but the city also has a strong record on education (with excellent secondary level schools as well as the expanding Magee University).

There has been a big increase in inward investment since the Troubles ended, with technology company Seagate Technology in particular playing a central role, employing over 1,000 people. Tourism has become an integral part of the city’s economy also, as has its role as a shopping centre. However, there was a monumental setback on that front earlier this year when the landmark Austin’s department store in the Diamond Area closed its doors with the loss of 54 jobs.

While Sinn Féin’s support has been creeping closer to that of the SDLP, it is still lagging behind. The party heavily backed former councillor Gearóid Ó hEára’s bid to take Mark Durkan’s Westminster seat last year, but, in the end, Durkan saw the challenge off comfortably with a little help from tactical unionist voting.

However, the SDLP will not be able to rely on any unionist or non-aligned vote this time, although the party should see more transfers arriving from these quarters in later counts.

What has made its third seat really vulnerable has been the arrival of the Sinn Féin big beast, Martin McGuinness, into the constituency. Although a native of Derry, he has been an MLA for Mid-Ulster, where he previously served as an MP.

His arrival back into Derry should galvanise the party’s vote and will provide a real threat to the SDLP. However, there is a sliver of a chance that if the third SDLP seat is vulnerable, it might fall to an Independent candidate, or to Eamonn McCann of the People Before Profit alliance.

The three SDLP MLA's are Colum Eastwood, Mark H Durkan (a nephew of the MP) and Gerard Diver. Eastwood was the last SDLP candidate elected in in 2011 but he has since become party leader and is expected to retain his seat easily. Likewise, Durkan has proven a solid vote-getter and should consolidate his mandate. The candidate who might be seen as vulnerable is Gerard Diver, who was co-opted last year, after the veteran MLA Pat Ramsay stood down. While a popular councillor, he will be in a huge battle for survival.

McGuinness is assured of a seat but there is no guarantee that the two sitting MLAs will also come through. His ‘celebrity’ status in his home town will need to be tempered with a strict vote management strategy to ensure the gap between him and the other two is manageable.

While republican veteran Raymond McCartney and Maeve McLaughlin have high profiles, the latter was co-opted in 2012 and her seat might be considered to be more at risk.

The DUP safely won the sole unionist seat in 2011 but the party has had internal turmoil since then. Maurice Devenney was co-opted to replace William Hay, but then stood down. He was replaced in April 2015 by Gary Midleton. Now Devenney is standing again as an Independent, but Midleton, an impressive young politician, should comfortably retain the DUP seat.

There are two candidates from outside the mainstream with potential to upset the status quo. Veteran activist and journalist McCann has not been all that far off before and has an outside chance of taking the last seat at the SDLP’s expense.

The same could be said for Dr Anne McCloskey, a general practitioner from the Shantallow area who is campaigning on an anti-abortion platform.

Prediction: There is only one seat in play and that is the third SDLP seat. The party might just hold on in the face of challengers from Sinn Féin, McCann and McCloskey.

SDLP (3); SF (2); DUP (1)

Candidates

Kathleen Bradly (Ind)

Maurice Devenney (Ind)

Gerard Diver (SDLP)

Alan Dunlop (NI Cons)

Mark H Durkan (SDLP)

Colum Eastwood (SDLP)

Mary Hassan (Greens)

Julia Kee (UUP)

John Lindsay (CISTA)

Eamonn McCann (PBP)

Raymond McCartney (Sinn Féin)

Chris McCaw (Alliance)

Anne McCloskey (Ind)

Martin McGuinness (Sinn Féin)

Maeve McLaughlin (Sinn Féin)

Gary Middleton (DUP)