London - 24 May 2016

1. Various aerials of Canary Wharf

London - 6 June 2016

2. Set up of Gina Miller, co-founder of wealth management company SCM Direct

3. SOUNDBITE (English) Gina Miller, co-founder of wealth management company SCM Direct:

"It could be terrible for the city because there is so much going on in the city, and we are seen as being one of the forefronts in the financial services and being a leader in that sector and if you look at all the modelling that has gone on there will definitely be a huge impact because a lot of the euro clearing happens in the UK. We have already seen that this first quarter of this year compared to last year, M and As - mergers and acquisitions - are down 39 percent, we've seen a real halt in foreign investment in the UK. If gilt markets - foreigners why would they want to buy our gilts, we could be hit in gilts we don't know what will happen with sterling. Nobody knows."

London - 24 May 2016

4. Aerial of the city

London - 22 May 2016

6. Pan of Bank of England

7. Pull focus from flowers to Bank

8. Workers and sign for Bank underground station

London - 24 May 2016

9. Set up of Jeffrey Evans, the Lord Mayor of the City of London

10. SOUNDBITE (English) Jeffrey Evans, the Lord Mayor of the City of London:

"Well, first of all it’s very important matter, it’s a, this is a decision that will affect future generations. The city of London we had, we reached a decision in March the corporation that we would take a position and that’s very strongly that we wish to remain in, it was a clear majority for that. And it’s, it’s very important the city of London is really, perhaps are most successful industry in the UK, recognises the financial, press and business services, we recogonise the importance of the EU to London and the UK."

London - 24 May 2016

11. Aerials of the city with the Shard and the Gerkhin

Bristol - 6 June 2016

12. Various of set up of Peter Hargreaves, co-founder of brokerage firm Hargreaves Lansdown

13. SOUNDBITE (English) Peter Hargreaves, co-founder of brokerage firm Hargreaves Lansdown:

"In addition to the cost of building the infrastructure for a rival to the City of London one has also got to work out whether people will want to live in another financial center. They certainly wouldn't want to live in Paris, although Paris is a pretty city, purely because of the tax rates and in all honesty they wouldn't want to live in Frankfurt because actually there isn't even the housing there to house them. People want to live in London it's got the best restaurants in the world, the best sport facilities in the world, the best theatres in the world, I mean why would anyone want to live anywhere else."

FILE: London - 22 February 2016

14. Various of trading floor and traders at GKFX brokers in London

Bristol - 1 June 2016

15. Set up Vicky Pryce, economist and former joint head of the U.K. government economic service

16. SOUNDBITE (English) Vicky Pryce, economist and former joint head of the U.K. government economic service:

"It is just possible, even if there is a 'Brexit vote', the UK we get some special allowance in terms of the way in which it operates, particularly in the service sector with the rest of Europe. But it will take some time for that to settle down, it will take some time for the negotiations to take place. There is a two year period during which officials and also ministers will have to sit down and try and negotiate a deal and we just don’t know whether even over that period something will come out that will be in the slightest bit beneficial for the city so, a lot of uncertainty. Uncertainty is bad news."

London - 24 May 2016

14. Aerials of the city

Gina Miller needs to look no further than her own small investment firm to know that leaving the European Union would be bad for Britain.

She has an analyst who is Italian: would he need a visa? She has customers who are British retirees living in Spain: will they return home to keep access to health care and liquidate their euro investments? Her firm, SCM Direct, works closely with French bank Societe Generale: would that relationship continue?

"It could be terrible for the city,'' she said suggesting the impact could be similar to the 2008 financial crisis.

From the international banks in the skyscrapers of Canary Wharf to the traditional home of Britain's financial industry in the City of London and the hedge funds of Mayfair, bankers and money managers across the capital are watching the June 23 referendum on EU membership with trepidation. Many fear a vote to leave would undermine London's position as the world's pre-eminent financial center and damage an industry that underpins the British economy.

In case of a British exit, or Brexit, from the EU, US banking giant JPMorgan said last week that they would have to move staff to the continent to ensure it could continue to serve clients who want to invest there, Dimon said. Other global banks with customers in the rest of the EU would be in a similar situation.

Britain has been the gateway to the EU for many banks, brokerages and fund managers for decades. In addition to having a trusted legal system and institutions that operate in English, the language of international finance, London is in the right time zone to access most of the Earth during its working day and has a reputation for delivering top-notch financial services. The industry is also surrounded by an ecosystem of expertise, lawyers, accountants and consultants, to support it.

Some 60 percent of all European headquarters of non-EU firms are based in the U.K., according to TheCityUK, which lobbies on behalf of the financial industry. The UK hosts more headquarters of non-EU firms than Germany, France, Switzerland and the Netherlands put together.

London's advantages are such that people in favor of leaving the EU, such as Peter Hargreaves, co-founder of brokerage firm Hargreaves Lansdown, think it will retain its luster no matter what. He poured scorn on the notion that it could be easily replicated.

"In addition to the cost of building the infrastructure for a rival to the City of London one has also got to work out whether people will want to live in another financial center,'' he said. "They certainly wouldn't want to live in Paris, although Paris is a pretty city, purely because of the tax rates and in all honesty they wouldn't want to live in Frankfurt because actually there isn't even the housing there to house them. People want to live in London.''

London's financial sector has complained about a number of EU rules, such as limits on bankers' bonuses and an attempt to impose a tax on financial transactions.

Those considerations, however, are largely trumped by concerns that leaving the EU would make access to the other 27 EU countries more difficult, many analysts say.

The principle of "passporting" currently allows any firm registered in one EU country to operate in any other member state without facing another layer of regulation. It's the same principle that allows exporters to ship their goods to any EU country free of tariffs. Losing that freedom is a particular concern for the many foreign firms who use London not only as a financial hub but as an entry point into the EU.

While the UK could probably negotiate a new arrangement for trade in goods, it would be much more complicated to hammer out a deal on services, experts believe. The situation has no precedent, no country the size of the UK has ever left such an integrated economic union, so the outcome of any talks can't be predicted.

And anything that curtails Britain's financial industry has implications for the UK economy as a whole, not just the bankers who were pilloried for taking home million-pound bonuses while they fueled the global financial crisis.

The industry's importance is even more obvious in Britain's trade figures. While the country posted an overall trade deficit of 34.4 billion pounds (50 billion US dollars) in 2014, it generated a 72 billion pound surplus from exporting financial and related services.

"Uncertainty is bad news," said Vicky Pryce, an economist and former joint head of the UK government economic service.

"It will take some time for that to settle down, it will take some time for the negotiations to take place. There is a two year period during which officials and also ministers will have to sit down and try and negotiate a deal and we just don’t know whether even over that period something will come out that will be in the slightest bit beneficial for the city so a lot of uncertainty

The City of London - the square mile roughly bounded by the walls of the original Roman city - has been the financial heart of Britain since the 17th century, when merchants meeting at local coffee houses formed Lloyd's of London and the London Stock Exchange. It has survived wars, famines and fires and would likely survive any outcome from the EU vote. The question is in what form.

Jeffrey Evans, the Lord Mayor of the City of London, whose office has promoted The City as place to do business since the Magna Carta was signed in 1215, says leaving the EU in not a risk worth taking.

Speaking in an opulent drawing room that feels more like a museum, with Dutch masters lining the walls, Evans noted that leaving the EU is "a very important matter."

"This is a decision that will affect future generations," he said.