Electoral Calculus have run their best estimate of the 2019 election result through the 2018 boundary proposal for 600 parliamentary seats (the case for which reduction may be hard to make in practice now as no Tory will want their own chance of a career sacrificed for the sake of a pointless reduction in numbers).
Approximate equalisation of numbers of voters per seat has this consequence:
Something much like this will happen. There is now no way to stop it.
Labour has to realise how hard that road back will be, especially with indiscipline, if it breaks out.
What is required from Labour? A commitment to total electoral reform: nothing less will do.