The reports, which were compiled by Cambridge Econometrics and come in the absence of any detailed Brexit assessments from Brexit secretary David Davis, explore the potential impact of five different Brexit scenarios on nine industrial sectors.
Even in the case of a two-year transitional deal and continuing membership of the Single Market and Customs Union, there could be 36,000 fewer science and tech jobs across the UK, 5,000 of them in London.
London’s chief digital officer, Theo Blackwell, said: “London’s science and tech sectors are some of the most innovative and exciting parts of our economy and are the rival of anywhere in the world for their dynamism and creativity.
“A no-deal Brexit runs the risk of completely undermining the growth and development of recent years and could see London fall way down the league table of global science and tech hubs.
“Government must take action to safeguard jobs, investment and growth, or else we risk turning back the clock on years of progress and threatening our future prosperity.”
Lloyd Dorfman, chairman of “click and collect” parcel service Doddle and a member of the mayor’s Business Advisory Board, said: “This report makes for worrying reading. As we negotiate our exit from the EU, I would like to see us retain as many of the benefits of the Single Market as possible.
“What should be front and centre is maintaining London’s position as the leading financial centre in the world, a vibrant place for entrepreneurship and a welcome city for all people to work and visit.”
Allbright co-founder Debbie Wosskow, who also sits on the Business Advisory Board, said the only way to limit the potential damage was to retain membership of the Single Market and Customs Union.
The analysis showed that, all told, the UK could lose 482,000 jobs and £50bn worth of investment, and the average growth rate could slow from 1.3% to 1.1%.
But this is not a precise forecast, and there remain many factors that could change these scenarios for better or worse – not least the precise details of any deal negotiated with the EU, or other countries.
“This is the first time that the various impacts of Brexit – trade, investment and migration – have been comprehensively assessed across a number of key indicators and sectors at sub-national level,” said Cambridge Econometrics director Ben Gardiner.
“Our analysis is particularly valuable to local leaders because it indicates the potential impact on employment and output of Brexit under a range of scenarios, which is necessary given the uncertainty surrounding the final outcome of negotiations.”
In December 2017, Sadiq Khan released a draft economic development strategy to help Londoners access tech jobs, increasing digital skills, funding for small tech companies, and growing digital infrastructure. Earlier this month, it emerged that despite the uncertainty around Brexit, London tech companies received more venture capital funding in 2017 than did all the other major European cities combined.