Who would be a population forecaster in these times?

The GLA have recently forecast that London will grow from 9M to 10.5M by 2050. But it is worth looking at the components of change. There is a big range of potential net international migration (+50K to +120k each year), a net loss of -100K people moving out to other parts of the UK (as has been occurring for years) and a high natural increase of around +55K a year due to the Capital's younger age structure. But all of this is constrained by housing delivery: past delivery of around 30K units/annum less than 60% of the housing targets of 52.287K. And if London's internationalised growth is constrained in the long term what does that mean for paying back the ￡370bn Covid Bill as well as providing the fiscal resources for Levelling Up and Net Zero transition? It is not just about cutting the cake differently. It is also about making sure the cake is getting bigger.