Mayor of London Sadiq Khan will once again reiterate the importance of full access to the single market for the financial services sector post Brexit on Monday evening.
The pro-business Mr Khan will use a keynote speech to business leaders at a dinner hosted by insurance market Lloyd's of London to fight the City's corner.
He will say: "Getting simple, easy and comprehensive access to the single market for our financial sector is not only central to London's ongoing status as the world's leading provider of financial and professional services.
"It is - by extension - key to our nation's economic stability and future growth. So the Government needs to be creative in its solutions, and ambitious in its negotiating platform."
"But I'm confident there is a workable deal to be agreed. A unique British deal that works for London. A deal that will enable London to remain a world-leading city for finance."
Since the EU referendum vote, the mayor has been angling for devolution of fiscal responsibility including tax raising powers, as well as more control over business and skills, housing and planning, transport, health and policing and criminal justice.
However, he has dismissed calls for London to be given City State status.
His comments come on the day that the chairman of Lloyd's, John Nelson, warned that the group could be forced to move parts of its business to the EU unless single market access is secured in a post-Brexit Britain,