Complex sentence: In March 2017, Hogg apologised for breaking the Bank of England's code of conduct and personal relationships policy, by not having declared a potential conflict of interest that her brother worked in the strategy office of Barclays, which was subject to Bank of England regulation.
Split into simpler sentences: In March 2017, Hogg apologised for having previously breached the Bank of England's code of conduct and personal relationships policy. She had failed to declare a potential conflict of interest in that her brother worked in the strategy office of Barclays, subject to Bank of England regulation.