I suppose i should add - obviously the biggest factor in the 2019 election was the brexit fudge keith and co levered corbyn into (OK oor keith, he didn't take much levering). If labour had stuck to the 2017 policy it could have been very different:

""Only half (52%) of those who voted leave in 2016 and Labour in 2017, stuck with the Labour party in 2019. A third (33%) moved directly to the Conservatives, while 6% voted for the Brexit party." etc