Confident assertions are being made about what will happen to the City after Brexit. Sir Charlie Bean, former deputy governor of the Bank of England, said last week that he had “absolutely no doubt at all” that euro-denominated clearing of interest rate derivatives would be moved into the European Union.

Then chancellor Philip Hammond said the exact opposite, suggesting the EU would be foolish to attempt such a manoeuvre because it would only hand business to New York. London, Hammond argued, benefits from economies of scale that EU countries shouldn’t try to smash out of “narrow and hypothetical national advantage”.

Such arguments go to the heart of the debate about the wisdom of allowing the London Stock Exchange to merge with Deutsche Börse, a £24bn deal that now faces about six months of regulatory scrutiny.

Before the vote for Brexit, the pitch from the pair was straightforward, almost compelling. The duo would be a European powerhouse to compete with the big US houses, led by ICE (owner of the New York Stock Exchange), and oil the wheels of the European economy. All that was required was for both sides to accept a new structure in which the holding company would be based in London but local regulators would continue to oversee local entities as if nothing had changed.

The structure is clever and shareholders duly approved the terms, so now it’s up to the regulators and politicians to protest if they wish. The European commission will fret about the possible loss of competition. The specific UK worry, however, is obvious: if, despite Hammond’s advice, EU governments try to slice off chunks of City business, are their chances improved by the LSE/Deutsche merger?

Hammond’s relaxed stance is understandable up to a point. The Frankfurt-based European Central Bank has always been infuriated that London dominates euro-denominated trading but it has lost one court battle on the matter and, say most lawyers, the UK’s exit from the EU wouldn’t alter the basis of the relevant judgment. What’s more, sensible EU business folk might complain if Berlin or Paris tried to undermine London; they would worry that the price of capital could go up for them.

All the same, Bean’s warning shouldn’t be dismissed lightly, or without proper scrutiny. It’s very odd, for example, that Xavier Rolet, chief executive of the London Stock Exchange, is in charge of studying market infrastructure for Baroness Vadera’s post-Brexit financial services taskforce; as an architect of the Deutsche deal, he’s hardly impartial.

What’s needed is a specific national interest study. If it concludes that the merger should be paused until the terms of Brexit are decided and proper assessments can be made, so be it. The Deutsche/LSE deal is too important to the City to be waved through on the merry assumption that things will probably work out OK in the end.

Who are the UK’s fat executives?

International trade secretary Liam Fox, if he had wanted to attack the UK’s “lazy” business culture seriously, could have pointed to the UK’s large balance of trade deficit and compared it with Germany’s surplus.

Fox didn’t do that, however. Maybe there were two reasons why. First, successful German exporters tend to enjoy more financial support from local and central government, which doesn’t suit Fox’s agenda. Second, the UK’s exports of goods and services per capita are the third highest in the G7, after Germany and Canada, as economist Andrew Sentance pointed out.

Downing Street declined to endorse Fox’s remarks. That was wise. Theresa May, let’s hope, will go further and invite Fox to shame those “fat” UK executives he thinks play golf on Friday afternoons instead of negotiating export deals. If the golf line was a throwaway, let’s hear about all the deals Fox thinks could have been done. Without evidence, his generalisations are absurd.

Exit Shafik

Deputy governors of the Bank or England are meant to last more than two years, so Dame Nemat Shafik’s escape to the London School of Economics is big news in the small world of central banking.

It’s hard to detect any falling-out in the glowing tribute from governor Mark Carney. And the Bank’s review of fair and effective markets, overseen by Shafik, received generally favourable reviews. So one assumes she really does find the pull of academia too great.

Yet it would be struggle to say Shafik has established a high profile. When she arrived from the IMF in August 2014, some people thought Carney had hired a potential successor; it’s been a while since that theory was aired.