Guy Sears, interim chief executive of the Investment Association, says Mifid II legislation on funds introduces a "paradigm shift" in transparency for the British investor and was one example of influenc by Brussels.
Speaking at the Morningstar Investment Conference today about Brexit he cited Mifid II as one of the pieces of EU legislation that would have a profound effect on UK fund management in the very near future.
Just one example, said, was the tighter control on inducements from fund managers to advisers such as invitations to sporting events or other entertainment. The FCA was already having to put this into effect and it was something that the sector would have to get used to.
It would be a "hugely dramatic" change, he said.
He told hundreds of delegates at the Morningstar Investment Conference in London today that Mifid II legislation would also ask fund managers about the total cost of ownership for the investor and "that's never happened before". It would ask what costs look like from the customer's point of view for the first time.
These were just some of the profound changes from the EU affecting the UK fund management sector and this could change radically if the UK voted for Brexit.
Overall, he said, there were many indications that EU membership had been to the UK's benefit but if the UK votes for Brexit the effects "either way" would be short term.
Asked what direct impact Brexit could have on the industry he said it would depend on the nature of each fund management company, with some more affected than others. Those who rellied on European 'passports' to sell around Europe would have to consider their strategy.
Ucits funds could also be impacted as most were domiciled in other EU states, he said, and a vote to leave would put the UK outside the EU and potentially Uctis legislation.
He said: "I can see some business models will see a real impact quite quickly and for others it will be more general and depend on the impact on the economy."