It's the ultimate irony. Britain's departure from the bloc was supposed to mean breaking loose from Europe's shackles and ushering in an era of light-touch regulation for the City of London.

But three years on, it’s British authorities who are lobbying the EU to impose stronger safeguards on a wobbly part of financial markets — whereas Brussels technocrats aren’t so sure.

Top U.K. officials from the Treasury, Bank of England and Financial Conduct Authority will raise concerns about the EU’s lax approach during a charm offensive this week in Belgium.

“There are different feelings on how fast things can move,” said one U.K. official, granted anonymity to speak freely because discussions between the two sides are confidential. “There is more impetus on the British side to move and move quickly lest something go wrong.”