The lord mayor of the City of London will add his voice to a growing chorus of business leaders urging Theresa May to strike a Brexit deal with the EU before negotiations draw to a close.

In a speech prepared for the Bankers and Merchants Dinner at Mansion House this evening, Andrew Parmley will stress that a Brexit deal which ensures access to the EU single market is 'vital' for City businesses.

'The City Corporation remains firm that access to the single market is a priority. For the firms I represent, and the millions they support, a deal is vital.

'We seek a bespoke agreement with the EU for reciprocal market access, based on the principle of mutual-recognition of our regulatory regimes.

'A bonfire of regulation would have no benefit.'

Mr Parmley's comments will be the latest that run counter to Prime Minister Theresa May's mantra that 'no deal is better than a bad deal' when it comes to negotiations with the bloc, raising concerns that the UK will have no replacement for passporting rights that ensure access to the single market for financial services after Brexit.

Other sectors fear that Britain will have to fall back on World Trade Organisation trading rules as it crashes out of the single market and customs union.

Mr Parmley, who will speak alongside chancellor Philip Hammond and Bank of England governor Mark Carney at Mansion House, is also expected to emphasise the importance of immigration for UK business.

Financial services, hospitality, farming and manufacturing trade bodies have all warned of calamity if the Tories follow through on a so-called hard Brexit, which would put hundreds of thousands of British jobs at risk.