Britain left the EU's orbit on Dec. 31 but a trade deal with the bloc does not cover financial market access, which is being handled separately under the EU's equivalence regime.
Brussels grants access if it deems that UK rules are equivalent or aligned enough to the bloc's regulations.
"The prize in terms of equivalence isn't to be sniffed at," John Taylor told parliament's Treasury Select Committee, using an informal term suggesting something valuable or worth having, in a hearing on his appointment to the BoE's Prudential Regulation Committee.
But taking advantage of the freedoms available in leaving the EU may be constrained by the desire to have the UK regime recognised as equivalent, he said.
BoE Governor Andrew Bailey said last week that Britain should not become a "rule taker", meaning having to copy EU rules in detail in return for access.
Britain and the EU began talks this week to agree on a memorandum of understanding that will allow regulators from both sides to cooperate, a step Britain hopes will unlock more access for the City.
Taylor, a former marketing director at Lloyds bank who has also held several roles at insurer Standard Life, said: "One would hope that further dialogue with the EU in these areas will result in the UK regime being accorded equivalence by the EU in the near future."
Taylor said the benefits of equivalence for UK insurers is not that valuable, though it could help some cross-border customers that may be stuck in limbo.
Instead, there was a lot to be gained from using freedom after Brexit to rewrite solvency rules for UK insurers.
The EU has granted access to clearing houses for derivatives in London, but only for 18 months to give banks time to shift positions from Britain to the EU.
This will need ongoing attention until a more enduring settlement is reached, Taylor said.
EU regulators on Wednesday warned UK banks not to dodge the bloc's rules in activities they don't have equivalence for.
(Reporting by Huw Jones; Editing by Alison Williams, William Maclean)
By Huw Jones
