Constituency profile: Dumbarton

Scottish Labour's Jackie Baillie has held the seat since 1999 but her lead, once considerable, was cut to just 109 votes in 2016.

It is the most marginal seat in Scotland. Jackie Baillie, Scottish Labour's deputy leader and a veteran of her party, has held the Dumbarton seat for more than two decades, but her lead – which was once considerable – has diminished.

Baillie was stand-in following Richard Leonard's resignation in January until Anas Sarwar took charge in March. She has been the constituency’s MSP since Holyrood was set up in 1999, reflecting her status as a politician of notable experience.

Over the years she has fought off competition from the SNP, but her majority – which in 2003 had reached 6,612 – was cut to just 109 votes in 2016. The closing gap has paved the way for a contest of increasing intrigue in next month's Scottish Parliament election, which will see SNP candidate Toni Giugliano try to win the seat for his party.

Baillie's performance as acting leader and as a member of the Holyrood harassment inquiry may well stand her in good stead as the vote looms.

She was widely considered to have been one of the more concise and effective individuals on the committee, which took evidence from Nicola Sturgeon and Alex Salmond among others, as it tried to get to the bottom of the government's botched internal probe.

The task facing the SNP and Giugliano is not insignificant, but the prospect of winning the diverse constituency - consisting of two local authorities in Argyll and Bute and West Dunbartonshire – is not beyond their reach.

A matter of contention is HM Naval Base Clyde, commonly known as Faslane, which sits on the northern shore of Gare Loch. It is home to the Royal Navy's Submarine Service, including its nuclear deterrent.

The SNP is firm in its opposition to Trident, the party's stance is that there should be no place for nuclear weapons in Scotland. Baillie, however, has supported its renewal, which put her at odds with party colleagues during the 2016 election. The SNP believes Faslane has a future as a conventional naval base, but the issue remains a key one for many constituents with employment links to the base and some may be uncertain over how change there may affect them.

Other candidates standing for election in Dumbarton include Maurice Corry, currently a Scottish Conservative list MSP for the West Scotland region, and Andy Foxall for the Scottish Liberal Democrats.

Looking at previous Scottish Parliament election results in Dumbarton, Giugliano, a mental health campaigner, will be considered the candidate with the best chance of challenging Baillie – the SNP have come within 2,000 votes in 2007, 2011 and 2016.  

We are just over three weeks from finding out if this will be the year that Baillie's time as a constituency MSP is to draw to a close. However, she is top of her party's regional list for West Scotland and is, therefore, set to return to Holyrood regardless.