Some of the City's biggest business groups have urged the Government to redouble efforts to maintain access to the single market, take a "sensible" approach to immigration and reject protectionism as part of Brexit negotiations.
The comments, from the likes of the Institute of Directors (IoD), the City of London Corporation and TheCityUK, come ahead of the 100-day anniversary of Britain's decision to quit the European Union.
Simon Walker, director general of the IoD, told the Press Association: "The Government must set out a positive vision for a free-trading Britain which is open to talent from anywhere in the world.
"That means resisting calls for protectionism and taking a sensible approach on immigration which recognises that in order to succeed, British companies need the skilled workers from the EU and beyond."
Mr Walker also said that since the initial shock of the Brexit vote is wearing off, and companies are feeling more optimistic, the Government must move quickly to underpin business confidence and ensure Britain remains open.
Post-referendum data has shown some resilience in the economy, but Mr Walker is urging the Chancellor Philip Hammond to introduce measures in the Autumn Statement that encourage businesses to spend.
"In the short-term, the Chancellor needs to take steps at the Autumn Statement, like raising the annual investment allowance to £1 million a year, that will encourage business to spend," he said.
Meanwhile, Mark Boleat, policy chairman at the City of London Corporation, reiterated the importance for the Square Mile's financial institutions to retain passporting rights, which allow them to do business in Europe.
"The number one issue for the City is the uncertainty that Brexit has caused. The general consensus within the Square Mile is that access to the single market with passporting rights will be important in ensuring sustained economic growth, and easy access to skilled labour is also a major need for businesses.
"There is also broad agreement that the UK cannot be a 'rule taker' and must have some say over future regulations that will affect financial and professional services."
Mr Boleat added that the Corporation, which governs the UK's financial district, is working through a "lengthy list" of what the City wants to see from the forthcoming Brexit negotiations.
Speculation is mounting that militant Tory eurosceptics could force the Government into a so-called "hard Brexit", whereby the UK would ditch the EU's single market, a move that many argue would be catastrophic for businesses and the economy.
Lobby group TheCityUK said that a "mutually beneficial" deal between the UK and the EU would be in both parties' interests.
Chief executive Miles Celic said: "Since the vote, the UK-based financial and related professional services industry has been focused on identifying and communicating to the UK Government its specific needs and priorities for the negotiations, as well as engaging with EU institutions and governments, and with key international partners.
"It is also a European asset given its role as Europe's financial centre, which is why ensuring a deal which is mutually beneficial for the EU and the UK, and ensuring stability and certainty to the extent possible, and protecting the interests of the industry's customers and clients, is in everyone's interests."
Their comments come after an array of City business leaders delivered a withering assessment of Theresa May's Brexit negotiations, with the likes of Ryanair boss Michael O'Leary and financial PR guru Roland Rudd rubbishing the Prime Minister's oft-used "Brexit means Brexit" mantra.