A 'no-deal' Brexit scenario could cost the UK £50 billion, according to new analysis commissioned by Mayor of London Sadiq Khan.
The report, carried out by Cambridge Econometrics, models five possible Brexit scenarios. This ranges from a near-status quo situation to a “lost decade” for the British economy.
It says the greatest impacts on gross value added (GVA) are expected to be in agriculture, manufacturing and construction, because these sectors are most exposed to high tariffs and non-tariff barriers.
The productivity impacts are expected to be strongest in sectors such as agriculture and construction, which are highly dependent on trade and skilled labour.
Mr Khan, a strong supporter of the remain campaign, has since argued for the UK to stay in the EU’s single market and customs union
He said: "This independent analysis should help guide the Government to the best outcome for London and the UK.
"If the Government continue 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.
"Ministers are fast running out of time to turn the negotiations around. A 'no deal' hard Brexit is still a very real risk - the worst possible scenarios."
'Irresponsible'
The London Mayor told BBC Radio 4's Today Programme that there is "no sector not negatively impacted."
"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."
For the British farming industry, there is worry of the catastrophe a ‘no deal’ scenario and moving to WTO ‘most-favoured nation’ status would bring, severely impacting the industry's ability to trade.
One report has concluded that a ‘no-deal’ outcome would lead to a collapse in agri-trade, with a 90% drop in beef exports and 53% drop in lamb exports from the UK to the EU.
It has led farming unions to state the need to secure a comprehensive free trade agreement with the EU as top of the agenda for the industry.
In a meeting with Defra minister George Eustice, NFU Cymru stressed the importance of the UK government securing continued "free and unfettered" access to EU markets upon the UK’s departure from the EU in March 2019.
'Major issue'
Trade with the EU is seen as critical to the Welsh food and farming sector, with around three quarters of its food and drink exports and nearly 40% of lamb being exported to the EU.
NFU Cymru President Stephen James said: "A ‘no deal’ scenario and moving to World Trade Organisation ‘most-favoured nation’ status - with Tariffs of 40% and more on many cuts of red meat - would be a major issue for Welsh agriculture and the wider rural economy."
Transport secretary Chris Grayling has previously claimed that the UK could become self-sufficient in food after a 'no-deal' Brexit.
Mr Grayling said that in the event of a no-deal Brexit, the UK would respond by growing more produce and importing from more places around the world, in order to prevent a rise of food prices.
However, NFU's Director of EU Exit and International Trade Nick von Westenholz said there will be 'considerable disruption' if a trade deal is not secured with the EU.
“Given the extent of our trade in food with the EU, failure to secure a comprehensive trade deal would cause considerable disruption to farming in the UK,” Mr Westenholz said.
