London mayor Sadiq Khan has warned a hard Brexit will cost the country 500,000 jobs and £50bn in potential investment.
According to an economic forecast he commissioned from Cambridge Econometrics, as many as 87,000 jobs would go in London alone.
The authors say that while every Brexit outcome would harm the UK economy, “the harder the Brexit, the more severe the economic damage could be”.
Nationally, a no-deal Brexit would see economic output in 2030 up to 3.3% lower than would be the case with the status quo.
Speaking on BBC Radio 4’s Today programme, Khan said: “It’s astonishing that the government has failed to do any proper impact assessments on what Brexit could mean for our economy.
“Their complete lack of preparation is irresponsible, leading to fears that they are putting party politics ahead of the national interest.”
The analysis shows that under the worst of the five scenarios modelled – leaving in March 2019 without a deal or transition arrangements in place – would see 482,000 fewer jobs across the country and a loss of £46.8bn in investment by 2030.
The bottom line is, however, that no one knows for sure what the impact of Brexit will be – whether that be hard, soft or somewhere in between.
Sam Woods, the deputy governor of the Bank of England, told a parliamentary committee in November that 75,000 job losses in London was a plausible number.
However, research carried out by the Financial Times, speaking to leaders and chief executives of scores of banks and finance firms, concluded job losses as staff are relocated to European hubs would likely be under 10,000.
And, of course, Theresa May and her Brexit team believe they can still secure a good trading deal for the UK that would see little long-term impact on the economy and jobs.
Khan stressed his commissioned research was the first to try to nail down proper figures on the impact of Brexit.
David Davis, the Brexit secretary, was widely ridiculed when he admitted comprehensive analysis on a variety of sectors and industries he said had been undertaken, in fact, had not.
MPs who saw these assessments said they amounted to little more than copying and pasting Wikipedia entries.
Philip Hammond, the chancellor, and Davis have been in Berlin talking to business leaders about the need for a bespoke trade deal that will include financial services – the so-called “Canada plus, plus, plus”.
And Theresa May was hosting heads of UK banks on Thursday to brief them on progress.