USA peers Goldman Sachs and Morgan Stanley are also looking at spreading staff across a number of European cities after Brexit.
Diplomats, who have been revising the document published by the European Commission two weeks ago, have added an entire section on "good faith".
Best for Britain, which has joined forces with other campaign groups and individuals, argues that the Brexit treaty "amends or replaces" EU treaties and should therefore be subject to the 2011 European Union Act, which introduced a "referendum lock" for laws with such wide-ranging consequences.
The British government says this was settled in negotiations previous year and that the European Union have changed the agreement.
Theresa May has committed to withdrawing from the customs union and single market, which would mean there would need to be border checks between Northern Ireland and the Republic of Ireland - this being the only land border the United Kingdom shares with the EU - whilst also insisting that one of her primary goals is to avoid a hard border within Ireland.
"From 2020-21 onwards, we have maintained our assumption that financial-sector profit growth will be weaker than the whole economy average, given that the sector is likely to be disproportionately affected by the UK's exit from the EU".More news: Game of Thrones finale will feature lots of major character deaths
"The time will come when you regret your decision", the president of the European Commission said, as Nigel Farage laughed and shook his head in disbelief. On Wednesday, EU Trade Commissioner Cecilia Malmstrom said that the 28-nation bloc could consider the introduction of responsive measures against certain groups of U.S. products.
EU President Donald Tusk issued a bold statement to Britain's Prime Minister Theresa May, saying that if talks about the UK's withdrawal from the bloc are to go ahead, she must find "realistic" proposals to avoid a hard border between Northern Ireland and the south.
"I could not agree more".
Mike Cherry, national chairman of the Federation of Small Businesses, said discussions over future trade deals were "clearly important" but the priority for firms now was getting clarity about the immediate future with the European Union after Brexit day. "I would, however, ask to allow us to define what's in the EU's interest".
For no trade border you need tariff-free trade and full alignment in rules and regulations, at least insofar as they apply to goods, including animals and food.
The recent suggestion by British prime minister Theresa May for a deal akin to that between the U.S. and Canada suggest something a little more intrusive than a few cameras reading auto licence plates. 72 per cent of trade in and out of Belfast Harbour is to Great Britain and less than one fifth to the EU. It therefore appears impossible to solve the problem of the Irish border given the self-imposed red lines of both the European Union and of Theresa May.