Constituency profile: Lancaster & Fleetwood
Lancaster & Fleetwood, which Jeremy Corbyn visited on Friday, is the sort of Labour-held seat that would be at risk in a Conservative landslide.
It ranks at number 64 on a list of Labour constituencies most vulnerable to the Tories.
Were it to change hands at the General Election on December 12, it would probably mean the Conservatives were on track for a comfortable majority in Parliament.
The seat has only been in existence since 2010.
It was held by the Conservatives until 2015, when it was narrowly won for Labour by Cat Smith.
She managed to increase her majority in 2017, from 1,265 to 6,661.
She also polled more than half of the vote (55%), with the Tories second (41%) and the Liberal Democrats far behind in third place (3%).
Ms Smith is standing again in 2019, along with candidates for the Conservatives, the Liberal Democrats, the Brexit Party and the Greens.
The Tories need a swing of 7.3% to take Lancaster & Fleetwood – not an easy undertaking.
But a swing of this size, if repeated across north-west England, could see up to 10 Labour seats falling to the Conservatives.
The entire region will be crucial in determining the result of the election – which is why Boris Johnson was also campaigning in the area on Friday.