Boris Johnson lost his majority in September when Conservative MP Phillip Lee dramatically crossed the floor of the House of Commons and defected to the Liberal Democrats.
Lee has given up his Bracknell seat - which will be contested between the Tories’ James Sunderland and the Lib Dems’ Kaweh Beheshtizadeh, who came to Britain as a Kurdish refugee 15 years ago - and is challenging Brexit hardliner Sir John Redwood in the next door seat of Wokingham.
When the campaign began the Lib Dem leader Jo Swinson talked of becoming the next prime minister and said she would revoke Article 50 but her style and substance has not gone down well with voters and her party still trails the Conservatives and Labour.
These 12 seats could tell the story of the election when the results are announced in the early hours of 13 December.
Jo Swinson herself has got a fight on her hands to hold onto her own seat, which is made of Milngavie and other fairly middle class suburbs on the north side of Glasgow.
The constituency has had a checkered past with MPs representing no less than four different parties since its formation in 1950.
— Michael Gibbons 🏳️🌈🏴 (@IndyMichael_G) December 8, 2019
Labour held it for most of that time, with the Conservatives controlling the seat for only six months in 1974.
In 2005 Swinson won East Dunbartonshire for the first time, and held it five years later as the Lib Dems went into coalition with the Tories.
She paid the price for that coalition and its austerity programme in 2015, when she was turfed out by the SNP’s John Nicolson, but she made a remarkable comeback two years later and regained the seat.
Now though she faces a strong challenge from a new SNP candidate, Amy Callaghan, and it will be interesting to see if Labour and Conservative supporters vote strategically for or against her.
The Conservatives had a majority of just 31 at the 2017 election in Southampton Itchen, one of the port city’s two constituencies.
Labour’s candidate, Simon Letts, said last month: “We had three recounts. What happened was that 100 Tory votes were wrongly put in our pile. It looked like we had one by 170. For 45 minutes, at about 3am, I thought I was going to be an MP. Then they were moved across and I lost by 31.”
If Letts wins this time and ousts the Tory MP Royston Smith it would be no great surprise but the scale of his victory is of perhaps more interest.
Labour has made much of the fact that a record 3.2 million people, many of them under the age of 25, have registered to vote this year and if the “youthquake” of 2017 has been replicated then Jeremy Corbyn could be looking quite cheerful on Friday morning.
Hastings & Rye
Another good result for Labour would be gaining Hastings & Rye, the former seat of ex-Home Secretary Amber Rudd.
Rudd announced only in October that she would not be seeking re-election and the local Conservatives chose Sally-Ann Hart as their new candidate. Hart is a councillor in the rural hinterland, lives in a quiet country lane and is married to a wealthy hedge fund manager.
One local resident in Hastings described her to Sputnik as “Amber Rudd on speed, a Brexiteer, very jolly hockey sticks, into hunting foxes, the lot.”
And her reputation was further enhanced - or destroyed - by a video of the hustings which went viral last week.
In it she tried to defend her view that disabled people should get less money because “they don’t understand money."
Then over the weekend it was reported Ms Hart will be investigated by the Conservative Party for alleged anti-Semitism for sharing a video in 2017 with an image suggesting Jewish billionaire George Soros controlled the European Union.
Labour’s Peter Chowney, who lost out by 346 votes in 2017, is hoping to beat Hart but the progressive vote could be split by Liberal Democrat Nick Perry, who told Sputnik: “Things are changing in the constituency and that’s why I genuinely believe I can win.”
At the 2017 election one of the biggest shocks was Labour winning Canterbury, the historic city in Kent which had been Conservative literally forever.
Rosie Duffield beat the long-time Tory MP Julian Brazier by just 187 votes and this time she will be up against Anna Firth, a barrister and Conservative councillor.
The Greens have deliberately not fielded a candidate, in the hope of helping Duffield retain her seat, but the Liberal Democrats have put up Claire Malcomson who could split the anti-Tory vote.
The city - which has been a constituency since 1295 - has a flourishing arts and music scene, energised by its increasingly diverse population and its 40,000 students. But it also has a number of dilapidated social housing blocks spread across the city, which Labour aims to target this year.
Last month Sean Connolly, 24, a PhD student, told Sputnik he would be voting for Jeremy Corbyn: “The policies and ideas put forward by the Labour Party gel the way I think the country should be run as opposed to the Tories or anyone else. Needs first over money, is the key point.”
The other huge shock was Emma Dent-Coad winning Kensington, by only 45 votes after several recounts.
The constituency has never been out of the news since - in June 2017 a fire broke out in Grenfell Tower in North Kensington, killing 72 people.
The tragedy encapsulated the division in Britain between the wealthy and the impoverished and Kensington is very much divided between the super-wealthy south of the consituency (which includes Harrods department store) and the north, which includes the gutted husk of Grenfell.
But Dent-Coad is really up against it to hold off a challenge from the Conservative, Felicity Buchan, and the resurgent Liberal Democrats who have picked a former Tory MP, Sam Gyimah, as their candidate.
Dent-Coad threatened to sue Gyimah at one point after he told City AM: “Many things went wrong and, by the way, Emma Dent Coad was on the council and was part of all the discussions that went on in terms of cladding.”
Dent-Coad complained to the police under the Representation of the People Act and said: “If this is a political game, shame on him. We’ve sent rebuttals with all the links and all the evidence is there. Even if I had been on those committees, there is no way that a backbench opposition councillor would have made those decisions. But I wasn’t on those committees at that time and I can prove it.”
But Gyimah has won the support of one Kensington resident, former Chancellor George Osborne, who now edits the Evening Standard newspaper.
Osborne said he was considering switching to the Lib Dems because of the candidate: “I like Sam. He’s bright and sensible. So do I vote for him, or for the party that – however wayward it’s become – gave me incredible
opportunities for 20 years? We’ll see, but old habits die hard.”
The ballot paper in Kensington includes several fringe candidates, including Harriet Gore, who is representing Touch Love Worldwide.
Gore, a Nigerian-born barrister, told Sputnik: "We don't need to be tearing people apart in Parliament...Love is an energy and it's an energy we all have....I think I am already winning because we are making people aware of a different way of doing things. People are saying we need this and we want this. The feedback has been very positive. I'm hoping that whoever gets in will be inspired by some of the things I am saying."
Cities of London and Westminster
A couple of miles east of Kensington sits another constituency which has acquired newfound status as a marginal this year.
The incumbent MP Mark Field decided to stand down after an embarrassing incident last year when he manhandled a female climate change protester.
Labour’s original candidate Steven Saxby, a vicar nicknamed the “Radical Reverend”, quit in October after a historic sexual harassment allegation was made, which he strongly refutes.
So the battle will be between Nickie Aiken, the leader of Conservative-run Westminster City Council, and Gordon Nardell QC, a lawyer who in July this year resigned as Labour’s in-house counsel overseeing the disciplinary process over anti-Semitism allegations within the party.
But the Liberal Democrats have high hopes that they can come from nowhere to win the seat, with their candidate Chuka Umunna, a former Labour MP who quit the party in February and chose not to run for the Lib Dems in Streatham.
Last month the Green Party candidate Zack Polanski told Sputnik he believed he could win: “If enough people in the City of London and Westminster decide they have had enough and want to tackle the climate emergency, Brexit and inequality then I will be walking into Parliament and representing them as their first Green MP. They will finally have someone on their side for the first time.”
Uxbridge & South Ruislip
It would of course be a historic night if Labour’s candidate Ali Milani gained Uxbridge, a seat which has been held by Boris Johnson since 2015.
If that came to pass it would be the first time in British political history that an incumbent prime minister had been turfed out.
The Conservative Party constitution says the leader of the party "shall be drawn from those elected to Parliament" but Johnson could technically stay on as prime minister for a few weeks - until a new leader is elected by the party - in the unlikely event that the Tories won the election but lost Uxbridge.
But Labour should not get their hopes up.
Uxbridge has never been won by Labour - even at the 1997 Tony Blair landslide it remained stubbornly Conservative.
In Wales, the Labour Party are largely seeking to hold onto seats in a part of the country which voted to leave the European Union and is keen to “get Brexit done”.
But one Conservative seat which is near the top of their targets nationwide is Preseli - which consists of the ports of Milford Haven and Haverfordwest in the far west of Wales.
Stephen Crabb has been the Tory MP there since 2005 and he was seen as a rising star in the Conservative Party until he was forced to resign after admitting sexting a 19-year-old girl in 2017.
A year earlier Crabb, the then Welsh Secretary, showed his ambition when he put in for the leadership after David Cameron resigned. He lost out to Theresa May, who subsequently promoted him to Pensions Secretary.
In Preseli he is defending a majority of just 314 against Labour’s Philippa Thompson, a former diplomat, who he beat in 2017.
West Bromwich East
Labour has had some bad election nights in the past - Tory landslides in 1979 and 1983, the disappointment of defeat in 1992 when Neil Kinnock thought he had it won, and 2010 when Gordon Brown lost power after 13 years - but if Labour lose West Bromwich East then 2019 could be every bit as bad.
The seat - in the heart of the Black Country - was held with huge majorities by Tom Watson, Labour’s Deputy Leader, since 2001 and his predecessor Peter Snape held it right back until the constituency was created in 1974.
Watson was set to be challenged by veteran left-winger George Galloway and former Tory MP Harvey Proctor, who had a personal grudge against Watson, who he blamed for encouraging the delusions of Carl Beech, who was jailed in July for making up stories about a murderous paedophile ring which supposedly included Proctor.
But Watson dramatically quit on 6 November and after a last-minute selection, Ibrahim Dogus was chosen as Labour’s candidate.
Dogus has no connection with West Bromwich - he is a Kurdish restaurant owner in north London, but has good connections with Jeremy Corbyn and others high up in the Labour Party.
With no Watson, Proctor stood down but Galloway is still on the ballot paper although Dogus’s biggest challenge will probably come from the Conservatives’ Nicola Richards.
Watson did have a 7,713 majority in 2017 but the constituency voted overwhelmingly (68 per cent to 31 per cent) to Leave in the 2016 referendum and if Boris Johnson’s “Get Brexit done” mantra chimes with the locals, Dogus could be beaten and Labour could be in for a long night.
Losing West Bromwich East to the Tories could be put down as a fluke result caused by the loss of a long-standing MP and his replacement by a parachuted “outsider”.
So our local MP here in Bridgend has... 1️⃣ Voted Against the Brexit Deal 3 times, 2️⃣ Voted to Block No Deal AND 3️⃣ Last night voted not to have a General Election either to break the deadlock MPs like her are causing! 🙄 She’s not the solution, she’s the problem!— Tom Giffard (@TomGiffard) September 5, 2019
But if Labour lost Bridgend in south Wales, it would signal a Tory landslide.
The seat is 67th on the Tories’ list of targets and if they win it Boris Johnson will certainly be returning to Downing Street with a sizeable majority.
Jeremy Corbyn might as well start writing his resignation letter if the Conservatives win Sedgefield in County Durham.
Labour has a majority of more than 6,000 in this seat, which was represented by a certain Tony Blair between 1983 and 2007.
But it voted 59 percent in favour of leaving the European Union in the 2016 referendum and many people in the North East of England feel they have been forgotten about by Jeremy Corbyn and his Cabinet, most of whom represent seats in Remain-supporting London.
Labour's Phil Wilson, who has held the seat since Blair stood down in 2007, will be hoping to fend off a Tory challenge from Paul Howell, a retired accountant. The Brexit Party is also fielding a candidate, which may help Wilson to hang on.
The Conservatives, Labour and the Liberal Democrats traditionally steer clear of Northern Ireland, leaving the battle to various local parties who largely draw support along sectarian lines.
Catholics vote for Sinn Fein or the Social Democratic and Labour Party (SDLP) while Protestants vote for the Democratic Unionist Party (DUP) or the Ulster Unionist Party (UUP).
— UTV (@utv) December 8, 2019
But a growing number of voters have been opting for the non-sectarian Alliance Party and they will be hoping to win Belfast South from the DUP’s Emma Little-Pengelly.
In 2017 Little-Pengelly won it from the SDLP’s Alasdair McDonnell and she is defending a majority of 1,996 against the SDLP’s Claire Hanna and the Alliance Party’s Paula Bradshaw.
If the DUP loses Belfast South it could be seen as punishment for their cack-handed handling of Brexit and the coalition with the Tories.