I thought I would take as my starting points what seems to be the internal debate inside the Labour party as to why it ended up where it did in the election. Thesis number one: it was Brexit wot did it. Thesis number two: it was being too left-wing wot did it.

I'm going to suggest that neither analysis, on its own, is adequate. Let's start with Brexit. There is no doubt that Brexit played an important role in explaining the change in party support between 2017 and 2019 (and indeed going back to 2015 as well).

Those who voted leave were much more likely to vote for the Conservatives or the Brexit Party than they were to vote for the Conservatives or UKIP back in 2017. Also, on the remain side, there was a clear relationship between having voted to remain in 2016 and voting for one or other of the parties that were in favour of having a second referendum.

Brexit is also absolutely fundamental to understanding the Conservative success because, at the end of the day, the Conservatives won by consolidating the leave vote. Nearly three-quarters of those who voted leave in 2016 voted for the Conservatives as compared with around 60 to 65 per cent in 2017. Whereas the remain vote was fragmented.

Labour got just under 50 per cent of the remain vote. The Tories still hang onto 20 per cent, although it was down as compared to 2017. And the Liberal Democrats were picking up around 20 per cent of the remain vote as well.

In the end, the reason why we have a pro-Brexit government is not because a majority of people voted in favour of Brexit but because of the differential concentration of support. It's also very clear that the pattern of movement between 2017 and 2019 is very clearly related to people's views on Brexit.

Labour lost between a quarter to a third of its leave voters in 2017 fell to the Conservatives. Equally, it lost around a fifth of its remain voters to the Liberal Democrats. So Labour Remainers and Labour Leavers, if they were defecting, were defecting in very different directions. This is something you can only explain as a result of their reaction to Brexit.

Brexit certainly creates awkward choices for Labour. The truth is that, on the one hand, it is predominantly a party of remain voters. But of course, the people who voted leave as a section of the electorate are those Labour thinks it represents - leave voters are more likely to be working class. It also causes the problem for Labour because Brexit is not a left-right issue.

People who we would classify, on the basis of responses to survey research, as left-wing were as likely to vote for Brexit as were those who are economically on the right. Many a person who voted leave is on the left economically. They don't like capitalism exactly the same way as they don't like immigration.

So there were difficult choices, but at the end of the day, Brexit was an issue where it became increasingly clear that you had to make a choice. It was a subject on which the middle ground of politics no longer existed. You either had to be a Remainer or Leaver.

I think one of the ironies of Jeremy Corbyn's leadership is that somebody who was widely criticised for being too extreme or too radical, in the end, crucified his leadership on the altar of compromise. He was the last person standing who wasn't willing to declare their position on Brexit. That was not something that was sustainable given where we had got to by December of last year. Of course, it simply reinforced another perception - a lack of leadership.

Brexit was a problem. It does create difficult choices, but was it handled as effectively as it could have been? I think no. Albeit the party would probably have had to bite the bullet on the subject in a way that it was reluctant to do.

The other arguments, coming particularly from those who are loosely associated with the regime of Tony Blair, is that the programme was too left-wing. The party was resurrecting ancient policies of nationalisation and it was wanting to restructure much of the private sector and the way it was governed.

The problem with the argument, that the positioning was too left-wing, however, is found by looking at the survey data as to people's attitudes towards nationalising utilities, towards changing the structure of company boards, it was actually relatively popular. Typically around 50 per cent of people said they were in favour. Only around a quarter were opposed. The free broadband policy was a bit of a niche market - it was young folk and Remainers who quite liked the idea.

Broadly speaking, leave voters weren't quite as keen on nationalisation as remain voters (many of them were ardent conservatives) but it's not clear that this stance was what was costing Labour its support amongst its leave-orientated voters. But here we come back to the question of leadership and competence. What voters were not convinced on was that Labour's programme for changing the public services, for changing the role of the state, was achievable.

So the proportion of people who thought this was achievable was less than the proportion of people who said that they quite liked the idea. More broadly, people said, 'is Labour going to be able to deliver? No. Can it run the economy? No.'

Unless those issues are addressed it is going to be very difficult for the party - whether it's on the centre or on the left in terms of political positioning - to be able to persuade the public as to whether it should be elected.

So in both cases, what the analysis needs to take on board is that it wasn't so much a crisis of ideology or a crisis of Brexit, but a crisis of the party. It is the party itself that has to convince people that it can govern the country.

That, I think, did mean hard choices on Brexit. It does mean being able to sell the vision that was meant to underline the policies, the individual policy programme. You needed an equivalent of 'Get Brexit Done'. There was no equivalent on the Labour side that explained in two short sentences what the policy programme was meant to achieve. That is as much as most voters are ever going to take on board.

Where does the party go from here? Well, you certainly need to understand where you are at. This is no longer a party that particularly gains the support of working-class voters. Although it does still do relatively well in places that you might call working-class communities. This, at the moment, is a party that has young people, it has graduates, and their distinctive characteristic is that they are socially liberal. These are the people who are remain-y. These are people who are not concerned about immigration. And so the question therefore is: where does the party go from here? Now, one possible answer is it needs to regain the voters it has lost.

Okay, fine. But bear in mind that many of these leave voters that Labour lost are older voters. They're frankly not going to be with us for that much longer. If you look at the age profile of the Conservative vote, unless that age profile is changed, the Conservatives are going to be in deep electoral troubled by 2030.

On the other side, if you say, well okay, actually now the party should run with the grain of what its got, which is young, socially liberal, university-educated voters, the difficulty there is that there is competition for that vote, which is from the Liberal Democrats.

I know it might appear that the Liberal Democrats didn't do terribly well but they are picking up enough of that vote to make life difficult. Whereas the Conservatives were able to extinguish UKIP in 2017 and extinguish Brexit in 2019. There is much more competition on that side.

Labour also, in coming to a decision, has to ask itself: do you really think you can compete with the Conservative party for the leave vote if the Brexit issue continues to be important in 2023 or 2024? Something that, frankly, we don't know the answer to. What, of course, is also true is that you need to not just simply fight the last war. Brexit may not be an issue in 2023 or 2024. Maybe it proves to be a success. Maybe we decide, as a country, to move on. Who knows?