The letter, addressed to Theresa May and signed by 40 representatives from across the Professional Business Services Council (PBSC), including the Advertising Association, Institute of Practitioners in Advertising, Market Research Society, Deloitte, Accenture and KPMG, outlines the conditions that should be met to guarantee a successful outcome for businesses following the UK’s departure from the EU.

"It is essential that we can continue to serve our clients and support the wider economy after the UK leaves the EU," the letter read.

To do this, it said businesses require the following from Brexit negotiations:

• Mutual recognition of professional qualifications, products and operating licences
• Mutual recognition of regulatory frameworks and regulators, including data protection, audiovisual media policy laws and statutory audits
• The ability of service providers to fly in-fly out to provide advice across the EU27 and trade across Europe
• Mutual recognition of judgments so deals across EU27 countries can proceed with legal certainty
• Continued co-operation in areas that facilitate trade – such as data sharing
• The ability to educate and recruit talent from overseas, from the EU and beyond
• Reduced uncertainty through any transition period.
  

Industries are at risk of facing a "distinct competitive disadvantage" if these needs are not met, according to the letter. "Failing to negotiate these elements would impair our ability to provide our services with the same range, depth and speed our clients around the world experience today, damaging their businesses," it read.

Stephen Woodford, chief executive of the AA, said: "Our advertising and marketing communications industry, which contributes over £120bn to GDP every year, is a vital and vibrant part of the UK’s professional business services sector and this is why we are supporting this letter from the PBSC.

"It is essential for our future that Brexit discussions and, ultimately, the post-Brexit agreement protect this jewel and enable further growth. Anything less will have damaging and long-lasting consequences on our economy and the wider society."