Even a softer scenario where Britain remains in the EU's single market, but leaves the customs union once the transition period is over, could result in 176,000 redundancies and a loss of £20 billion ($26.9 billion) in investments.
The report compares four possible post-Brexit scenarios to the option of maintaining the status quo - already ruled out by the British government - of staying in the European single market and customs union.
Elsewhere, if the United Kingdom ended up with the so-called Norway option - remaining in the single market but eventually leaving the customs union - the United Kingdom could still be hit with more than 175,000 fewer jobs and a drop of almost £19bn in investment.
"If the Government continues to mishandle the negotiations we could be heading for a lost decade of lower growth and lower employment".
"The analysis concludes that the harder the Brexit we end up with, the bigger the potential impact on jobs, growth and living standards".
And then came a report from recruitment firm Morgan McKinley claiming that London finance job vacancies fell 37% year-on-year in December, plus a Cambridge study warning that 87,000 fewer jobs will be created in London in the event of a "hard Brexit".
The impact assessments could infuriate the Government, which has insisted such information could undermine negotiations.
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There will also be an "edible factory", an amphitheater, and an area for attendees to camp in glamorous style, or "glamping". Hickman told TheBlast.com that the undeveloped land will be cultivated and that Tyson Ranch will be an "oasis".
Khan commissioned the research after Brexit secretary David Davis said the government had failed to analyse the potential impact of Brexit on specific sectors.
"Their complete lack of preparation is irresponsible leading to fears that they are putting party politics ahead of the national interest".
"There is no sector not negatively impacted", Mr Khan told BBC Radio 4's Today programme.
The analysis from Cambridge Econometrics said the worst case scenario - leaving the European Union in March 2019 with no deal or arrangements in place - would result in 482,000 fewer jobs, including 87,000 lost in London, and a loss of £46.8bn in investment by 2030. There would be 11,000 fewer jobs in science and technology, 5,000 fewer jobs in construction and 6,000 fewer jobs across London's creative sector.
Sadiq Khan said that while he was "heartbroken" about Brexit he had come to accept the results of the 2016 EU Referendum but his use of the word "probably" is likely to rile numerous 17.4million Brits who voted for freedom from the Brussels bloc.
Both the London mayor and Cambridge Econometrics admit that this analysis is not a precise forecast of what will happen.