Growth in the legal sector could halve by 2025 if the UK leaves the EU without a trade deal, a professional body has warned.

According to estimates from the Law Society, the legal sector would grow by 2.2% annually between 2019 and 2025 if the UK pursued a “soft” Brexit, and remained inside the customs union and the single market.

However, this growth could slip to 1.1% if the UK exits under a “no deal” scenario and adopts rules set by the World Trade Organisation (WTO), the Law Society said.

Opting for a “no deal” over a soft Brexit could wipe almost £3 billion from the turnover of the sector as a whole, according to the figures, which were compiled with Thomson Reuters.

The Law Society has also forecast that by 2025 there could be 4,000 to 5,000 fewer people employed in the legal sector if the UK agrees a Canada-style free trade agreement with the EU.

However, the society estimates this figure could rise to 10,000 if the UK leaves the EU under WTO rules.

Christina Blacklaws, president of the Law Society, said: “UK legal services look to have been relatively buoyant through 2017-18, thanks to a combination of Brexit-related work, steady demand from UK businesses and an uptick in business from non-UK clients taking advantage of the depreciation of the pound.

“However, Brexit is likely to have a significant negative impact on the legal sector in the medium and longer term.

“This is largely due to the knock-on impact of Brexit on the wider economy as demand for legal services relies on the success of other sectors in the UK economy.”

However, she said the society was “standing on thin ice” with its economic forecasts because global markets were volatile, and there was little agreement in the Brexit negotiations so far.