A former trade minister has made an impassioned plea for the UK to stay in the European Union to ensure the continued prosperity of domestic professional services.

Lord Green of Hurstpierpoint said UK membership was a ‘critical factor’ in our trading strength as we seek to promote and export legal services to the rest of the world.

Writing for City campaign group TheCityUK, Lord Green said a new generation of bilateral EU trade agreements has led to exciting opportunities for UK professional services in key markets such as South Korea and Singapore.

‘Put simply, the UK would not exert the same negotiating leverage from outside as it does within the EU,’ he said. ‘The scope of the UK’s financial and related professional services for generating foreign exchange earnings is linked to the UK’s EU membership.’

Green, a former chairman of the HSBC group, warned that withdrawal from the EU would throw the UK’s trade relations with the rest of the world into doubt.

He added that at a time when the UK, like the EU as a whole, increasingly relies on growth in other markets for its own wealth-creation, ‘we cannot afford that risk or the uncertainty that would accompany it’.

Lord Green said the ‘for’ case will have to be strongly made if a referendum on UK membership of the EU were to take place, putting forward positive economic arguments that should convince voters to stay in.

‘I have seen from both the business and government perspectives just how much the UK benefits from being a member of the EU in terms of trade and investment policy,’ he said.

‘The EU’s ”Common Commercial Policy” has been a success story for the UK. The EU’s trade partners want access to the entire EU Single Market (often for their industrial goods, in return for which the EU gains more open markets for services in which it has a competitive advantage).

‘Negotiating as a bloc gives the EU added power, which the UK would not enjoy on its own.’