Admiral Group is considering moving its European headquarters to Ireland if the British exit from the EU affects its ability to sell products across Europe.
If leaving means it loses the right to sell because of Britain losing "passporting rights" which allow financial firms to trade in the EU without having to set up locally regulated operations, Admiral says it will go.
Chief financial officer Geraint Jones said, "If passporting is withdrawn then Dublin would be one of the places within Europe where we might look to base our European underwriting from."
"There is probably more logic in being based in a place where we already have an infrastructure and an operation," he added.
Dublin has the advantages of a similar operating environment to the UK, native English speakers, and lower corporation taxes.
The company is one of the UK's largest insurance providers, its market share is more than 11%. It also operates in Italy, Spain, and France.
Like all aspects of the British process of withdrawing from the EU, it is impossible to tell whether UK firms will maintain these rights.
So far some of the EU's key leaders have offered a combative response to the referendum result. Access to markets is likely to come at the cost of concessions on the control of the movement of people to and from the UK.
