Let's call the second obstacle the "rural problem". Labour's brand is toxic in much of the West Country, city commuter belts, rural Wales, North Yorkshire, Cumbria and most constituencies centred on market towns with a rural hinterland. This toxicity is tied to a sense that Labour "can't be trusted on the economy" or is too extreme to be in power.

The Scottish and rural problems are gifts granting the Conservatives a clear message and strategy for maintaining a majority for years to come. These two problems require, I believe, three solutions - all hard to achieve. Let's start with the hardest: defeating the SNP.

I really like many of the SNP's MPs at Westminster. Indeed, Labour and Lib Dems in England tend to think broadly warm thoughts about the Scottish Nationalists, who are largely centre-left social democrats. But to achieve a non-Tory UK government we must defeat them comprehensively.

I haven't got an oven-ready plan for beating the nationalists. I simply say, progressives in England and Wales must recognise the SNP is Boris Johnson's secret weapon. Perhaps the plan starts by seeking to convince progressives in Scotland that they are vital to stopping the Tories, and they can only do that within the UK.

If you are a Scottish non-Tory, join the fight - and ditch the SNP wholesale. Stop being tempted by the rickety lifeboat and help us achieve a mutiny that wrests lasting control of the ship from the evil Tory captain!

The second solution: detoxify Labour. At present, Labour's brand is so terrifying that it pushes voters into Conservative arms (which is one reason why the Lib Dems also struggled to win seats in 2015, 2017 and 2019).

Solving this rests on the character and image of Labour's new leader. Party members must overcome their obsession with ideological purity at the expense of winning power. I, too, am repulsed by the notion of power without principles: but if you care about people in need, you can't fixate on principles without power. Labour must learn how to win again. For the sake of the country.

In 2015 and 2017, along with most of our seats, we lost vote share to the extent that we slipped from second to third place or worse in dozens of constituencies. Our 2019 silver lining is our return to second in around 100, mostly Conservative, seats. If we win many of those, then the Conservatives lose their majority. The path to a progressive majority is clearer.

The three solutions are connected. The Lib Dems' chances of winning these seats are hugely enhanced by the SNP's defeat and Labour detoxifying.

Bluntly, the enemies of a progressive, united Britain are the nationalists and the Tories. To fight them we need to develop humility and self-awareness and learn to work together.

Let's start with my party. The Lib Dems must accept that Labour provides the main vehicle for defeating the Conservatives in most areas. Labour must accept that their brand is a huge asset to the Conservatives, and that, across swathes of the country, the Liberal Democrats have the best chance of defeating Conservatives.

Labour and the Lib Dems need to accept that co-operation is necessary and desirable. We must then collectively deploy a ruthless will to win, in order to do the good we can only do in power.

Tim Farron is the Liberal Democrat MP for Westmorland and Lonsdale. He led the party between 2015 and 2017