The City of London will remain gripped by Brexit uncertainty when it marks 30 years since the Big Bang sent technological change sweeping through the capital's financial district.
Thursday will usher in three decades since Margaret Thatcher pushed the button on deregulation of the financial markets, signalling the demise of face-to-face trading on the stock exchange floor in favour of electronic trading on screens.
The move - coined the Big Bang because of the rise in market activity when the London Stock Exchange's (LSE) rules changed on October 27, 1986 - was taken by Mrs Thatcher to help Britain embrace global trading and break-up the anti-competitive status quo.
It heralded an era of booming business for the City, as international investment banks swooped on the capital and helped London become a global financial centre.
However, any celebrations underscoring this seminal moment risk being overshadowed by concerns over the City's future in a post-Brexit world.
Richard Lumb, group chief executive of Accenture's financial services, said the Big Bang "opened the door to global competition in a way that has completely transformed London".
But he does not expect Britain's vote to leave the European Union will diminish London's standing in the world of global finance.
He said: "There are legitimate concerns on what the Square Mile will be like post Brexit, but many of the worst case fears for the future of the City are exaggerated.
"The elements that make London a great financial centre will remain including flexible employment laws, a safe and respected legal and regulatory environment and world class support industries."
JP Morgan, HSBC and Goldman Sachs all said prior to the vote that thousands of jobs in the City of London could be moved to the continent in the event of Brexit.
These concerns have intensified since the EU referendum result, with a report by TheCityUK suggesting that a so-called ''hard Brexit'' - where Britain leaves the single market in order to take a tighter grip on immigration - could cost the City 75,000 jobs.
Industry concerns following the Brexit vote have centred around the UK's membership of the single market and whether it will continue to have access to the bank passporting system.
Banks and financial firms wanting to trade with a country in the European Economic Area (EEA) must apply for a passport, which allows them to sell their products to any country within the EEA.
Chancellor Philip Hammond has attempted to soothe the worries of the City by stating that it needs will be a ''very high priority'' for the Government in its Brexit negotiations.
But while the Government becomes embroiled in the process of unstitching Britain from the EU, rival European financial centres have mounted a major charm offensive in a bid to encourage international banks to shift their operations out of Britain to maintain a smooth trading relationship with Europe.
Sylvie Bermann, French ambassador to Great Britain and Northern Ireland, told the British Bankers' Association (BBA) conference that the French were looking to capitalise on Britain's vote for Brexit by wooing financial firms to Paris.
She said on Thursday that it was ''fair competition - that's what we learnt from the British''.
Anthony Browne, chief executive of the BBA, compounded the concerns last week, stating that b ank bosses have their hands ''poised quivering over the relocate button'' as Britain embarks on its exit from the European Union
The threats to the City posed by the Brexit vote are a stark contrast from the fallout of the Big Bang, which gave foreign banks a gateway to the EU.
The change came from the scrapping of both fixed commission charges and the historic distinction between stockjobbers, the market makers who bought and sold shares, and stockbrokers, who gave advice to clients.
While it was hoped it would lead to the rise of a number of large-scale British investment banks, the structural changes focused on smaller City firms being taken over by US and European investment banks.
David Buik, market commentator at Panmure Gordon and Co, said the Big Bang "stopped the cartel and it made the world unbelievably competitive".
"It wasn't a success for British banks, but for global banks it was massive success and that is why London became so important."