At every general election there are MPs who buck the national trend and hold on to their seats, sometimes by the most slender of margins.
In 2017, the SNP won Fife North East by a majority of just two, making it the most marginal seat in the country.
Other constituencies that saw wafer-thin victories in 2017 included Kensington (a Labour majority of 20), Perth & Perthshire North (an SNP majority of 21) and Southampton Itchen (a Tory majority of 31).
All these seats will be watched closely on Thursday to see if the winning party in 2017 will be able to increase their majority – or whether the party that missed out so narrowly last time round will be victorious.
Here are the most marginal seats being contested in this election, together with the majority of the winning party in 2017.
Fife North East (won by the SNP in 2017): 2
Kensington (Lab): 20
Perth & Perthshire North (SNP): 21
Dudley North (Lab): 22
Newcastle-under-Lyme (Lab): 30
Southampton Itchen (Con): 31
Richmond Park (Con): 45
Crewe & Nantwich (Lab): 48
Glasgow South West (SNP): 60
Glasgow East (SNP): 75